Uplink control channel resource allocation for an enhanced downlink control channel of a mobile communication system

ABSTRACT

Uplink control channel resource allocation for an enhanced downlink control channel is disclosed. A first example method disclosed herein includes receiving, at a user equipment (UE), a downlink control channel carrying a physical uplink control channel (PUCCH) resource indicator, mapping the PUCCH resource indicator to a first offset, mapping a position of the downlink control channel to a second offset, and mapping a linear combination of the first and second offsets to an index identifying a first PUCCH resource. A second example method disclosed herein includes, in response to receiving, at a UE, an indication of a dynamic resource offset in an enhanced physical downlink control channel (ePDCCH) transmitted in a first ePDCCH set, determining a position of the ePDCCH and a subframe offset, and processing the indication of the dynamic resource offset, the position and the subframe offset to determine an allocated uplink control channel resource for the UE.

RELATED APPLICATION(S)

This patent claims the benefit of and priority from U.S. ProvisionalApplication Ser. No. 61/679,037, entitled “UPLINK CONTROL CHANNELRESOURCE ALLOCATION FOR AN ENHANCED DOWNLINK CONTROL CHANNEL” and filedon Aug. 2, 2012. This patent also claims the benefit of and priorityfrom U.S. Provisional Application Ser. No. 61/753,731, entitled “UPLINKCONTROL CHANNEL RESOURCE ALLOCATION FOR AN ENHANCED DOWNLINK CONTROLCHANNEL” and filed on Jan. 17, 2013. U.S. Provisional Application Ser.Nos. 61/679,037 and 61/753,731 are hereby incorporated by reference intheir respective entireties.

FIELD OF THE DISCLOSURE

This disclosure relates generally to mobile communication systems and,more particularly, to uplink control channel resource allocation for anenhanced downlink control channel of a mobile communication system.

BACKGROUND

In prior mobile communication systems that are compliant with the ThirdGeneration Partnership Project (3GPP) long term evolution (LTE)standard, the detection status of a physical downlink shared channel(PDSCH) received at a user equipment (UE) device is reported back to anevolved Node B (eNB) of the network over a physical uplink controlchannel (PUCCH). Because multiple UE devices may each transmit a PUCCH,the network allocates a portion of the total resources available forPUCCH communications, referred to herein as a PUCCH resource, for use bythe UE device to report its PDSCH detection status to the eNB. In suchprior systems, the UE device determines the PUCCH resource(s) allocatedto the UE device for reporting PDSCH detection status from informationreceived in, or otherwise associated with, a physical downlink controlchannel (PDCCH) used to provide scheduling information for the PDSCH.

Future LTE mobile communication systems are being developed to supportan enhanced PDCCH (ePDCCH) for providing control channel information toUE devices. In such systems, a UE device may monitor and receive PDSCHscheduling information via an ePDCCH instead of, or in addition to, thePDCCH.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example mobile communication systemcapable of supporting uplink control channel resource allocation for anenhanced downlink control channel as disclosed herein.

FIG. 2 illustrates an example downlink LTE subframe supported by theexample system of FIG. 1.

FIG. 3 illustrates an example LTE downlink resource grid supported bythe example system of FIG. 1.

FIG. 4 illustrates example ePDCCH regions supported by the examplesystem of FIG. 1.

FIG. 5 is a flowchart representative of a first example UE process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIG. 6 is a flowchart representative of a first example eNB process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIGS. 7-8 illustrate example operations of the example processes ofFIGS. 5-6.

FIG. 9 is a flowchart representative of a second example UE process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIG. 10 is a flowchart representative of a second example eNB processfor performing uplink control channel resource allocation for anenhanced downlink control channel in the example system of FIG. 1.

FIGS. 11-13 illustrate example operations of the example processes ofFIGS. 9-10.

FIG. 14 is a flowchart representative of a third example UE process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIG. 15 is a flowchart representative of a third example eNB process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIG. 16 illustrates an example operation of the example processes ofFIGS. 14-15.

FIG. 17 is a flowchart representative of a fourth example UE process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIG. 18 is a flowchart representative of a fourth example eNB processfor performing uplink control channel resource allocation for anenhanced downlink control channel in the example system of FIG. 1.

FIG. 19 illustrates an example operation of the example processes ofFIGS. 17-18.

FIGS. 20-22 illustrate example performance results for the exampleprocesses of FIGS. 17-18.

FIG. 23 is a flowchart representative of a fifth example UE process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIG. 24 is a flowchart representative of a fifth example eNB process forperforming uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

FIG. 25 is a block diagram of an example processing system that mayexecute example machine readable instructions used to implement some orall of the processes of FIGS. 5, 6, 9, 10, 14, 15, 17, 18, 23 and/or 24to implement uplink control channel resource allocation for an enhanceddownlink control channel in the example system of FIG. 1.

Wherever possible, the same reference numbers will be used throughoutthe drawing(s) and accompanying written description to refer to the sameor like parts, elements, etc.

DETAILED DESCRIPTION

Methods, apparatus, systems and articles of manufacture (e.g., physicalstorage media) to enable uplink control channel resource allocation foran enhanced downlink control channel are disclosed herein. For example,some such disclosed methods are performed in/by a UE device, such as amobile device, to determine an allocated uplink control channel resourceusing a position of a transmission. Some such example methods (e.g.,which may correspond to example solutions #1 and #2 disclosed below)include receiving the transmission and determining its position. Suchexample methods can also include normalizing the position by a size ofthe transmission to form a normalized resource index. Such examplemethods can further include processing the normalized resource index(e.g., using a mapping function) to determine the allocated uplinkcontrol channel resource, and transmitting using the allocated uplinkcontrol channel resource.

For example, the allocated uplink control channel resource cancorrespond to an allocated PUCCH resource for positive/negativeacknowledgement (e.g., ACK/NACK) reporting by the UE device in an LTEmobile communication system. In such examples, the transmission receivedby the UE device can correspond to an ePDCCH grant message, and theposition of the transmission can correspond to a starting enhancedcontrol channel element (eCCE) index of the ePDCCH grant message.

Additionally, some such example methods can further include receiving anindication (e.g., such as a table) of a set of possible uplink controlchannel resources. Such example methods also include determining ademodulation reference signal (DMRS) identifier that corresponds to aDMRS with which the UE device may decode the transmission. Such a DMRSidentifier can include, for example, a multi-user multiple input andmultiple output (MU-MIMO) layer identifier, an antenna port index, aDMRS scrambling index, etc., and/or any combination thereof. Also, insuch example methods, the processing of the normalized resource indexcan include mapping the normalized resource index and the DMRSidentifier to at least one uplink control channel resource in the set ofpossible uplink control channel resources.

Additionally or alternatively, some such example methods can furtherinclude receiving an indication of an uplink control channel offset(e.g., such as a PUCCH resource offset). In such examples, theprocessing of the normalized resource index can include processing thenormalized resource index and the uplink control channel offset (e.g.,using the mapping function) to determine the allocated uplink controlchannel resource.

Other disclosed example methods (e.g., which may correspond to examplesolution #3 disclosed below) performed in/by a UE device to determine anallocated uplink control channel resource include receiving informationrelated to specification of a plurality of uplink control channelresource regions. Such example methods can also include receiving anindication specifying an allocated uplink control channel resourceregion from among the plurality of uplink control channel resourceregions. Such example methods further include selecting a first uplinkcontrol channel resource within the allocated uplink control channelresource region as the allocated uplink control channel resource. Forexample, a position (e.g., a starting eCCE) of a received transmission(e.g., a received ePDCCH grant) can be mapped to index a particularuplink control channel resource within the allocated uplink controlchannel resource region. As another example, a hash function can be usedto process input information, such as a UE identifier, a subframe indexover which a transmission is received, etc., or any combination thereof,to index a particular uplink control channel resource within theallocated uplink control channel resource region.

Still other disclosed example methods (e.g., which may also correspondto example solution #3 disclosed below) performed in/by a UE device todetermine an allocated uplink control channel resource can includereceiving, at the UE, a downlink control channel carrying a PUCCHresource indicator. Such example methods can also include mapping thePUCCH resource indicator to a first offset, the first offset varyingaccording to a subframe index. Such example methods can further includemapping a position of the received downlink control channel to a secondoffset. Additionally, such example methods can include mapping a linearcombination of the first and the second offset to an index identifyingthe first allocated PUCCH resource, and transmitting a PUCCH on thefirst allocated PUCCH resource.

In some such examples, a majority of magnitudes of the second offset aresmaller than a maximum magnitude of the first offset.

In some such examples, the downlink control channel is an enhancedphysical downlink control channel (ePDCCH).

Some such example methods further include normalizing the position ofthe received downlink control channel to form a normalized resourceindex, mapping the normalized resource index to form the second offsetand determining a third offset from an index of an antenna port used bythe received downlink control channel. Such example methods can alsoinclude mapping a linear combination of the first, second, and thirdoffsets to the index identifying the first allocated PUCCH resource.

Additionally or alternatively, in some such examples, the UE receives aplurality of physical downlink shared channel (PDSCHs), respective onesof the PDSCHs being received in respective different subframes. In suchexamples, the mapping of the linear combination can include adding afirst subframe offset corresponding to a first subframe in which a firstone of the PDSCHs was received. For example, the first subframe offsetcan increase monotonically with an index corresponding to a subframe inwhich a PDSCH was received.

Some such example methods can include determining a second allocatedPUCCH resource, the second allocated PUCCH resource having a value equalto the first allocated PUCCH resource plus a constant. Such examplemethods can also include transmitting a PUCCH on one of the first or thesecond allocated PUCCH resources using a first antenna port.

Some such example methods can include determining a second allocatedPUCCH resource, the second allocated PUCCH resource having a value equalto the first allocated PUCCH resource plus a constant. Such examplemethods can also include transmitting a PUCCH on the first allocatedPUCCH resource using a first antenna port and on the second allocatedPUCCH resource using the second antenna port, the PUCCH beingtransmitted simultaneously on the first and second antenna ports.

Yet other disclosed example methods (e.g., which may correspond toexample solution #4 disclosed below) performed in/by a UE device todetermine an allocated uplink control channel resource using a positionof a transmission include receiving the transmission and determining itsposition. For example, the transmission may correspond to an ePDCCHgrant message and the position may correspond to a starting eCCE indexof the ePDCCH grant message. Such example methods also includedetermining a scaled index and a first group index from the position.Such example methods further include permuting the first group index todetermine a second group index. Such example methods also includeprocessing the scaled index and the second group index (e.g., using amapping function) to determine the allocated uplink control channelresource, and transmitting using the allocated uplink control channelresource.

Further disclosed example methods (e.g., which may correspond to examplesolution #5 disclosed below) performed in/by a UE device to determine anallocated uplink control channel resource for an enhanced downlinkcontrol channel can include determining a position, such as a startingeCCE index, of the enhanced downlink control channel in a first enhanceddownlink control channel set. Such example methods can also includedetermining a number of channel elements, such as a number of eCCEs,based on a second enhanced downlink control channel set, and determininga subframe offset based on the determined number of channel elements.For example, the second enhanced downlink control channel set may be thesame as or different from the first enhanced downlink control channelset and, thus, may not correspond to the first enhanced downlink controlchannel set in which the enhanced downlink control channel is received.Such example methods can further include determining the allocateduplink control channel resource based on the determined position of theenhanced downlink control channel and the subframe offset, andtransmitting using the allocated uplink control channel resource.

Additionally, some such example methods can further include determiningthe allocated uplink control channel resource based on the determinedposition of the enhanced downlink control channel, the subframe offsetand a dynamic offset. For example, the dynamic offset may be obtained bythe UE device from the received enhanced downlink control channel.

In some examples, such methods can determine the subframe offset basedon a selected one of multiple enhanced downlink control channel sets,where the multiple downlink control channel sets are indexed, and theselected set is the set that has the smallest index. In some suchexample methods, the number of channel elements is determined from theselected set.

In other examples, such methods can determine the subframe offset basedon a maximum number of channel elements that the UE device can expect inany subframe according to a configuration of the second enhanceddownlink control channel set.

Still further disclosed example methods (e.g., which may also correspondto example solution #5 disclosed below) performed in/by a UE device(e.g., which may be operating in time division duplex (TDD) mode) todetermine an allocated uplink control channel resource for an enhanceddownlink control channel can include, in response to receiving, at theUE device, an indication of a dynamic resource offset in an enhanced(ePDCCH) transmitted in a first ePDCCH set, determining a position ofthe ePDCCH and determining a subframe offset. For example, the subframeoffset can include a first term corresponding to a first subframe,wherein the first term is based on a number of eCCEs and depends on acondition associated with receiving a downlink control channel duringthe first subframe. Such example methods can also include processing, atthe UE device, the indication of the dynamic resource offset, theposition and the subframe offset to determine the allocated PUCCHresource, and transmitting a PUCCH on the allocated PUCCH resource.

In some examples, the subframe offset includes a sum of terms thatincludes the first term. In some examples, the number of eCCEscorresponds to a number of eCCEs included in the first ePDCCH set. Insome examples, the number of eCCEs corresponds to a number of eCCEsincluded in a second ePDCCH set configured for the UE, the second ePDCCHset being different from the first ePDCCH set. For example, the numberof eCCEs included in the second ePDCCH set can correspond to a largestnumber of eCCEs from among a plurality of ePDCCH sets configured for theUE. In some examples, the dynamic resource offset is an integer value ina range from negative two to positive two.

Some such example methods can also include calculating the first termbased on the number of eCCEs and depending on the condition, wherein thecalculating includes setting the first term equal to the number of eCCEswhen the UE monitors the ePDCCH in the first subframe, and setting thefirst term equal to zero when the UE does not monitor the ePDCCH in thefirst subframe.

Some such example methods can also include, in response to not receivingePDCCH in the first subframe, when the UE receives a PDCCH transmission,determining the allocated uplink control channel resource according to aprocedure based on receiving the PDCCH transmission, wherein theprocedure is not based on receiving the ePDCCH.

Corresponding example methods (e.g., which may correspond to examplesolutions #1 through #5 disclosed below) performed in/by an access node(e.g., an eNB) to enable a UE to determine an allocated uplink controlchannel resource for an enhanced downlink control channel are alsodisclosed herein. For example, such methods (e.g., which may correspondto example solution #3 disclosed below) can include transmitting, to theUE, an indication in a control channel specifying (or related tospecification of) an allocated PUCCH resource region, which may includea plurality of PUCCH resources, from among a plurality of PUCCH resourceregions. For example, the indication can be carried in an ePDCCH. Suchexample methods can also include receiving a PUCCH from the UE on anallocated PUCCH resource selected from among the plurality of PUCCHresources included in the allocated PUCCH resource region. Additionally,some such example methods can further include sending, to the UE,information related to specification of the plurality of PUCCH resourceregions. For example, such information may be signaled to the UE throughradio resource control signaling. Additionally or alternatively, suchinformation may include a common parameter based on characteristics ofthe plurality of PUCCH resource regions. Additionally or alternatively,in some such example methods, two or more of the plurality of PUCCHresource regions can overlap.

Other disclosed example methods (e.g., which may also correspond toexample solution #3 disclosed below) performed in/by an access node(e.g., an eNB) for allocating a PUCCH resource can include transmitting,to a UE, a downlink control channel (e.g., an ePDCCH) carrying a PUCCHresource indicator. Such example methods can also include mapping thePUCCH resource indicator to a first offset, the first offset varyingaccording to a subframe index. Such example methods can further includemapping a position of the transmitted downlink control channel to asecond offset. Additionally, such example methods can include mapping alinear combination of the first and the second offset to an indexidentifying the first allocated PUCCH resource. Some such examplemethods further include receiving a PUCCH from the UE in the allocatedPUCCH resource.

Some such example methods can further include normalizing the positionof the transmitted downlink control channel to form a normalizedresource index and mapping the normalized resource index to form thesecond offset. Such example methods can also include determining a thirdoffset from an index of an antenna port to be used at the UE to receivedownlink control channel. Such example methods can further includemapping a linear combination of the first, second, and third offsets tothe index identifying the allocated PUCCH resource.

In some such examples methods, a plurality of PDSCHs is to betransmitted to the UE, respective ones of the PDSCHs being transmittedin respective different subframes. In such examples, the mapping of thelinear combination can include adding a first subframe offsetcorresponding to a first subframe in which a first one of the PDSCHs isto be transmitted. For example, the subframe offset can increasemonotonically with an index corresponding to a subframe in which a PDSCHis to be transmitted.

Some such example methods include determining a second allocated PUCCHresource, the second allocated PUCCH resource having a value equal tothe first allocated PUCCH resource plus a constant. Such example methodscan also include receiving a PUCCH from the UE on at least one of thefirst or the second allocated PUCCH resources.

Still other disclosed example methods (e.g., which may correspond toexample solution #5 disclosed below) performed in/by an access node(e.g., an eNB) for allocating a PUCCH resource can include determiningan indication of a dynamic resource offset, determining a position of anePDCCH, and determining a subframe offset for a UE. For example, thesubframe offset can include a first term corresponding to a firstsubframe, wherein the first term is based on a number of eCCEs anddepends on a condition determined in the access node and associated withthe UE receiving a downlink control channel during the first subframe.Such example methods can also include transmitting the indication in theePDCCH, the ePDCCH being located at the position.

Some such example methods further include determining the PUCCH resourceto be allocated to the UE based on the indication, the position and thesubframe offset. Such example methods can also include receiving a PUCCHfrom the UE in the PUCCH resource.

In some such examples, the number of eCCEs corresponds to a number ofeCCEs included in the first ePDCCH set. In some such examples, thenumber of eCCEs corresponds to a number of eCCEs included in a secondePDCCH set configured for the UE, the second ePDCCH set being differentfrom the first ePDCCH set. For example, the number of eCCEs included inthe second ePDCCH set can correspond to a largest number of eCCEs fromamong a plurality of ePDCCH sets configured for the UE.

Some such example methods further include calculating the first termbased on the number of eCCEs and depending on the condition, wherein thecalculating includes setting the first term equal to the number of eCCEswhen the UE is to monitor the ePDCCH in the first subframe, and settingthe first term equal to zero when the UE is not to monitor the ePDCCH inthe first subframe.

These and other example methods, apparatus, systems and articles ofmanufacture (e.g., physical storage media) to enable uplink controlchannel resource allocation for an enhanced downlink control channel aredisclosed in greater detail below. For example, as described below, oneor more of the example methods/solutions disclosed herein can correspondto and/or be implemented by operations performed by a machine inresponse to executing machine readable instructions, which are stored ona tangible machine readable storage medium (e.g., such as a tangiblestorage device, disk, etc.). In some examples, one or more of theexample methods/solutions disclosed herein can correspond to and/or beimplemented by operations performed by a suitably configured apparatus,such as an example uplink control channel resource allocator implementedby hardware and/or a processor with memory.

As noted above, a UE device in an LTE mobile communication systemreports the detection status of data received via a PDSCH using a PUCCHresource allocated to the UE device. In prior LTE systems, the UE devicecan determine its PUCCH resource allocation from information receivedin, or otherwise associated with, a PDCCH used to provide schedulinginformation for the PDSCH. However, future LTE mobile communicationsystems are being developed to support an ePDCCH, which is differentfrom the PDCCH, for providing control channel information, includingPDCCH scheduling information, to UE devices. Example methods, apparatus,systems and articles of manufacture (e.g., physical storage media)disclosed herein enable PUCCH resource allocation to be performed usinginformation received in, or otherwise associated with, an ePDCCH used toprovide scheduling information for a PDSCH to be received by the UEdevice.

Turning to the figures, a block diagram of an example mobilecommunication system 100 supporting uplink control channel resourceallocation for an enhanced downlink control channel as disclosed hereinis illustrated in FIG. 1. In the illustrated example, the mobilecommunication system 100 corresponds to an LTE mobile communicationsystem and includes an example UE device 105 in communication with anexample eNB 110 or, more generally, an example access node 110. The UEdevice 105 is able to receive data from the eNB 110 over exampledownlink (DL) channels 115. The DL channels 115 can include, forexample, one or more PDCCHs, one or more ePDCCHs, one or more PDSCHs,etc., which are described in greater detail below. The UE device 105 isalso able to transmit data to the eNB 110 over example uplink (UL)channels 120, which can include, for example, one or more PUCCHs asdescribed in greater detail below.

In the illustrated example of FIG. 1, the UE device 105 and the eNB 110include respective functionality to support operation in anLTE-compliant mobile communication system, such as the system 100.Additionally, the UE device 105 includes an example UE uplink controlchannel (UCC) resource allocator 125 to implement UE functionality forperforming uplink control channel resource allocation, such as PUCCHresource allocation, for an enhanced downlink control channel, such asan ePDCCH, as disclosed herein. Similarly, the eNB 110 includes anexample eNB UCC resource allocator 130 to implement eNB functionalityfor performing uplink control channel resource allocation, such as PUCCHresource allocation, for an enhanced downlink control channel, such asan ePDCCH, as disclosed herein. Example implementations and operationsof the UE UCC resource allocator 125 and the eNB UCC resource allocator130 are described in greater detail below.

The example UE device 105 of FIG. 1 can be implemented by any type ofuser device, mobile station, user endpoint equipment, etc., such as asmartphone, a mobile telephone device that is portable, a mobiletelephone device implementing a stationary telephone, a personal digitalassistant (PDA), etc., or, for example, any other type of UE device.Furthermore, although one UE 105 and one eNB 110 are illustrated in FIG.1, the example system 100 can support any number and/or type(s) of UEdevices 105 and/or eNBs 110. Accordingly, uplink control channelresource allocation, as disclosed herein, can be performed with multipleUE devices 105 and/or eNBs 110 in a mobile communication system, such asthe system 100. Moreover, the example system 100 may support othercommunication standards and/or functionality in addition to LTE mobilecommunications.

In an LTE system, such as the example system 100, PDCCHs can be used tocarry DL control information (DCI) from an eNB, such as the eNB 110, toone or more UEs, such as the UE device 105. The DCI can include, forexample, DL or UL data scheduling information, or grants, for one ormore UEs. Such scheduling information may include a resource allocation,a modulation and coding rate (or transport block size), the identity ofthe intended UE or UEs, and/or other information.

A PDCCH could be intended for a single UE, multiple UEs or all UEs in acell, depending on the nature and content of the scheduled data. Forexample, a broadcast PDCCH can be used to carry scheduling informationfor a PDSCH that is intended to be received by all UEs in a cell, suchas a PDSCH carrying system information about the eNB. A multicast PDCCHcan be intended to be received by a group of UEs in a cell. A unicastPDCCH can be used to carry scheduling information for a PDSCH that isintended to be received by only a single UE. In cells where relays orsimilar components are used, the downlink control information may becarried by a relay PDCCH (R-PDCCH) or a similar channel type. Any suchtype of channel will be referred to herein as the PDCCH. By decodingPDCCHs in a subframe, a UE knows the location of a DL data transmissionscheduled to itself in the current DL subframe, and/or the location ofan UL resource assignment for itself in a future UL subframe.

FIG. 2 illustrates an example DL LTE subframe 210 that can be supportedby the example system 100 of FIG. 1. Control information is transmittedin a control channel region 220 and may include a physical controlformat indicator channel (PCFICH), a physical hybrid automatic repeatrequest (HARQ) indicator channel (PHICH), and a PDCCH. The controlchannel region 220 includes the first few OFDM (orthogonal frequencydivision multiplexing) symbols in the subframe 210. The number of OFDMsymbols for the control channel region 220 is either dynamicallyindicated by PCFICH, which is transmitted in the first symbol, orsemi-statically configured in the case of carrier aggregation in, forexample, LTE Release-10 (Rel-10).

Also referring to FIG. 2, a PDSCH, a physical broadcast channel (PBCH),a primary synchronization channel/secondary synchronization channel(PSC/SSC), and a channel state information reference signal (CSI-RS) aretransmitted in a PDSCH region 230 of the subframe 210. DL user data iscarried by the PDSCH channels scheduled in the PDSCH region 230.Cell-specific reference signals are transmitted over both the controlchannel region 220 and the PDSCH region 230.

The PDSCH is used in LTE to transmit DL data to a UE. The PDCCH and thePDSCH are transmitted in different time-frequency resources in a LTEsubframe as shown in FIG. 2. Different PDCCHs can be multiplexed in thePDCCH region 220, while different PDSCHs can be multiplexed in the PDSCHregion 230.

In a frequency division duplex system, a radio frame includes tensubframes of one millisecond each. A subframe 210 includes two slots intime and a number of resource blocks (RBs) in frequency as shown in FIG.2. The number of RBs is determined by the system bandwidth. For example,the number of RBs is 50 for a 10 megahertz system bandwidth.

An OFDM symbol in time and a subcarrier in frequency together define aresource element (RE). A physical RB (PRB) can be defined as, forexample, 12 consecutive subcarriers in the frequency domain and all theOFDM symbols in a slot in the time domain. An RB pair with the same RBindex in slot 0 (represented by reference numeral 240A in FIG. 1) andslot 1 (represented by reference numeral 240B in FIG. 1) in a subframecan be allocated together to the same UE for its PDSCH.

In an LTE system, such as the example system 100, multiple transmitantennas can be supported at the eNB for DL transmissions. Each antennaport can have a resource grid as illustrated in the example of FIG. 3.As shown in FIG. 3, a DL slot includes seven OFDM symbols in the case ofa normal cyclic prefix configuration. A DL slot can include six OFDMsymbols in the case of an extended cyclic prefix configuration. Tosimplify the following discussion, subframes with the normal cyclicprefix configuration will be considered hereinafter, but it should beunderstood that similar concepts are applicable to subframes with anextended cyclic prefix.

FIG. 3 shows an example LTE DL resource grid 310 within each slot 240A/Bin the case of a normal cyclic prefix configuration. The resource grid310 is defined for each antenna port or, in other words, each antennaport has its own separate resource grid 310. Each element in theresource grid 310 for an antenna port corresponds to a respective RE320, which is uniquely identified by an index pair of a subcarrier andan OFDM symbol in a slot 240A/B. An RB 330 includes a number ofconsecutive subcarriers in the frequency domain and a number ofconsecutive OFDM symbols in the time domain, as shown in FIG. 3. An RB330 is the basic unit used for the mapping of certain physical channelsto REs 320.

For DL channel estimation and demodulation purposes, cell-specificreference signals (CRSs) are transmitted over each antenna port oncertain predefined time and frequency REs in every subframe. CRSs can beused by UEs to demodulate the control channels. Resource element groups(REGs) are used in LTE for defining the mapping of control channels,such as the PDCCH, to REs. An REG consists of either four or sixconsecutive REs in an OFDM symbol, depending on the number of CRSconfigured. A PDCCH is transmitted on an aggregation of one or severalconsecutive control channel elements (CCEs), where one CCE consists ofnine REGs. The CCEs available for a UE's PDCCH transmission are numberedfrom 0 to N_(CCE)-1. In LTE, multiple formats are supported for thePDCCH.

Downlink control information (DCI) is transmitted on the PDCCH and isused to allocate resources and assign other attributes for a shared datachannel in a downlink or uplink. The PDCCH can occupy 1, 2, 4 or 8 CCEsdepending on scheduling by the eNB. Larger CCEs can transmit a largenumber of physical bits, and consequently a lower code rate can beachieved, assuming the DCI payload size is the same. Therefore, a UEnear a cell edge may use a greater number of CCEs than one near the cellcenter.

UE-specific reference signals, which can also be referred to asdemodulation reference signals (DMRS), are used for PDSCH demodulationand are transmitted on antenna ports p=7, p=8, or one or several of p ∈{7, 8, 9, 10, 11, 12, 13, 14}. DMRSs are transmitted only in the RBsupon which the corresponding PDSCH for a particular UE is mapped.

With the introduction new features in LTE systems, the PDCCH capacityalone may not be enough to support a large number of UEs in a cell. Oneapproach for PDCCH capacity enhancement is to transmit DCI in an ePDCCHresiding in the legacy PDSCH region 230. The set of RBs and OFDM symbolsreserved for an ePDCCH can be referred as an ePDCCH region. An examplesof a possible ePDCCH region 410 in a PDSCH region 230 is illustrated inFIG. 4. The time and frequency resources of the illustrated exampleePDCCH region 410 may be configurable. Also, the PDCCH region 220 in asubframe may or may not be present in a subframe containing one or moreePDCCH regions 410.

PUCCH resource allocation in a LTE Rel-10 system is now described. InLTE, the detection status (e.g., in terms of acknowledgment and negativeacknowledgment indications, abbreviated as Ack/Nack or A/N) of adownlink PDSCH at a UE is reported back to eNB over PUCCH in the uplink.When a single carrier is deployed at the eNB, PUCCH format 1a or format1b is used to carry the A/N information, depending on whether one or twotransport blocks are carried in the PDSCH. For frequency division duplex(FDD) operation in an LTE system, the PUCCH resource for carrying theA/N information on the first antenna, denoted as p₀ or {tilde over(p)}₀, at a UE is implicitly signaled to the UE by the index of thefirst CCE used to transmit the corresponding PDCCH for the PDSCH. Asspecified in 3GPP Technical Specification (TS) 36.213, V10.1.0 (Mar. 30,2011), which is incorporated herein by reference in its entirety, the UEcan derive the PUCCH resource for the first antenna using the followingequation:

n _(PUCCH) ^((1,{tilde over (p)}) ⁰ ⁾ =n _(CCE) +N _(PUCCH) ⁽¹⁾.  Equation 1

In Equation 1, n_(PUCCH) ^((1,{tilde over (p)}) ⁰ ⁾ is the PUCCHresource index, n_(CCE) is the index of the first CCE used to transmitthe PDCCH that scheduled the PDSCH, and N_(PUCCH) ⁽¹⁾ is an offset valueconfigured by higher layer signaling. For two antenna port transmissionby the UE, the PUCCH resource for the second antenna port, denoted as p₁or {tilde over (p)}₁, is determined by the UE using the followingequation:

n _(PUCCH) ^((1,{tilde over (p)}) ¹ ⁾ =n _(CCE)+1+N _(PUCCH) ⁽¹⁾.  Equation 2

Because the set of PDCCH candidates or the UE specific search space(UESS) for a UE can vary subframe by subframe, the CCEs used for PDCCHtransmission to the UE can also change. Accordingly, the PUCCH resourcederived from the first CCE of a PDCCH can also vary. Therefore, theimplicit resource for the PUCCH can be in different RBs depending on thesubframe in which the corresponding PDCCH is received.

When more than one carrier is deployed by the eNB through carrieraggregation (CA), either PUCCH format 1b with channel selection or PUCCHformat 3 may be configured to carry A/N information. In the case ofPUCCH format 1b with channel selection, up to four (4) Ack/Nack bits canbe supported, which means that PUCCH format 1b can be used to supporttwo carriers. Channel selection can provide more Ack/Nack bits thanPUCCH format 1b by selecting among multiple PUCCH resources. Therefore,multiple PUCCH resources are allocated to each UE. The resources areallocated differently depending on if PDCCHs are transmitted on aprimary cell (PCell) or a secondary cell (SCell), and up to two or fourPUCCH resources are signaled by PDCCHs on SCell and on PCell,respectively. For FDD operation in an LTE system, PUCCH resource(s)corresponding to a PDSCH scheduled by a PDCCH on the PCell is(are)derived by the UE using the following equation:

n _(PUCCH,j) ⁽¹⁾ =n _(CCE) +N _(PUCCH) ⁽¹⁾.   Equation 3

In Equation 3, j ∈ {0,1, . . . , A-1} is the PUCCH resource index and A∈ {2,3,4} is the total number of PUCCH resources available to a UE inthe subframe. For FDD operation in an LTE system with a transmissionmode that supports up to two transport blocks, an additional PUCCHresource n_(PUCCH,j+1) ⁽¹⁾ corresponding to a PDSCH scheduled by a PDCCHon the PCell is determined by the UE using the following equation:

n _(PUCCH,j+1) ⁽¹⁾ =n _(CCE)+1+N _(PUCCH) ⁽¹⁾   Equation 4

The PUCCH resource(s) corresponding to a PDSCH scheduled by a PDCCH onthe SCell is(are) signaled to a UE explicitly by a combination of higherlayer and physical layer signaling, which is referred to as explicitresource allocation. For example, four PUCCH resources for the SCell aresemi-statically configured by higher layer signaling for a UE. One ortwo of the four resources can then be selected dynamically through thePDCCH. Two bits of the PDCCH (e.g., two transmit power control (TPC)bits transmitted in DL grant) on the SCell are used as A/N resourceindication (ARI) bits. One PUCCH resource is indicated for eachcombination of ARI bits.

In contrast to implicit signaling, explicit PUCCH resources addressed bythe ARI are semi-statically allocated to each UE, and therefore do notmove between PUCCH PRBs unless the UE is reconfigured using higher layersignaling. Since an implicitly signaled PUCCH resource can occupydifferent RBs on a subframe by subframe basis, but an explicitlysignaled PUCCH occupies the same RB until the UE is reconfigured, theexplicit and implicit PUCCH resources may not be in the same PUCCH PRB.

The explicit PUCCH resource(s) corresponding to each ARI state areindependently signaled such that they can be positioned anywhere in thePUCCH resource. This means that the PUCCH resources can be, but are notnecessarily, configured to be in the same PRB.

In the case of PUCCH format 3, the PUCCH resource is also explicitlysignaled by higher layer signaling.

Further aspects of the ePDCCH are now described. Building on thedescription provided above, in LTE Release 11 (Rel-11), PDCCHenhancement will be introduced by allowing transmission of both downlinkand uplink control channel information (e.g., DCI) over the legacy PDSCHregion to support increased control channel capacity, inter-cellinterference management and new LTE features, such as coordinatedmulti-point transmission (CoMP). This enhanced PDCCH is generallyreferred to as an ePDCCH. The minimum time-frequency resource unitallocated to an ePDCCH is referred as an enhanced control channelelement (eCCE). An eCCE consists of a predefined number of resourceelements (REs) within two physical resource blocks (PRBs) in adjacentslots (e.g., corresponding to a single resource block pair). An eCCE maybe further divided into multiple enhanced resource element groups(eREGs). An ePDCCH may be transmitted over one or multiple eCCEs,referred to as aggregation levels. The position of an eCCE is identifiedwith a non-negative integer eCCE index.

There can be one or two ePDCCH transmission modes configured to a UE ina subframe, referred to as a localized mode and a distributed mode,respectively. Localized and distributed ePDCCHs can either share thesame PRB pairs or use different PRB pairs.

For at least localized ePDCCH transmission, it is envisioned that a UEwould be informed by an eNB about the PRB pairs over which an ePDCCH maybe transmitted to the UE, which may also be referred to as an ePDCCHregion, as described above. For example, it is envisioned that the eCCEsover these PRB pairs would be indexed starting from the first possibleeCCE location in these PRB pairs. In some examples, UEs may beconfigured with different PRBs and thus the eCCE indexing is local to aUE or, in other words, is UE specific. In other examples, a set ofcommon PRB pairs are configured for a group, or all, UEs in an area andthe eCCEs are instead indexed over this set of common PRBs known to theUEs receiving the ePDCCH. In either example, an index uniquelyidentifies the eCCE regardless of whether the ePDCCH is transmitted inlocalized or distributed mode.

In each subframe, a UE will search over a set of ePDCCH resources (alsoreferred to as ePDCCH candidates) that may contain a grant for the UE ateach ePDCCH aggregation level. The resources for the ePDCCH candidatesmay change from one subframe to another. The set of ePDCCH candidates ateach aggregation level is referred to as a search space. For ePDCCHdemodulation purposes, one of the four demodulation reference signal(DMRS) ports (e.g. 7 to 10) may be used by the UE for channel estimationin ePDCCH detection in the case of localized ePDCCH. Either the same ordifferent DMRS ports may be allocated to different ePDCCH candidates ateach aggregation level. The DMRS port allocation can be eitherexplicitly signaled by the eNB or implicitly derived based on thelocation of the ePDCCH among ePDCCH resources and/or other parameters,such as UE ID, etc., or any combination thereof. For distributed ePDCCHtransmission, any one or multiple DMRS ports may be allocated to anePDCCH candidate.

Multiple ePDCCHs may be transmitted over different multiple inputmultiple output (MIMO) layers to different UEs using multi-user MIMO(MU-MIMO) transmission. In such examples, different MU-MIMOtransmissions may occupy the same set of eCCEs and, thus, thetransmissions are not distinguishable by eCCE indices alone. However,the MIMO layers transmitted to the UEs may be distinguished by whichDMRS is used for their transmission. The DMRS may be associated with anantenna port and/or a scrambling index.

It is envisaged that ePDCCH may be transmitted in a common search space(CSS) or a UE specific search space (UESS). When transmitted in a commonsearch space, multiple UEs may search for an ePDCCH in the same set ofeCCEs, and this set of eCCEs is broadcast to the UEs in a message on acommon control channel, or specified such that the set of eCCEs is knownto the network and UEs (e.g. by including the values of the set inphysical layer specifications). Because UE specific signaling is notneeded to determine the common search space, UEs can receive grants inan ePDCCH common search space while not in connected mode. This canreduce signaling overhead and enable reception of ePDCCH without the UEbecoming radio resource control (RRC) connected, thereby allowingstand-alone operation of a carrier containing only ePDCCH.

The eCCEs of a UE specific search space are determined using variablesor parameters that are specific to a particular UE, such as a randomsequence initialized by a UE identifier (ID) or a value signaled to theUE using radio resource control (RRC) signaling. Because UE specificsearch spaces for different UEs may occupy different eCCEs, this canallow the ePDCCHs for multiple UEs to be multiplexed, improving spectralefficiency for ePDCCH.

It is possible that the index of an eCCE could be determined differentlyin a CSS than in an UESS. When they are determined differently, the eCCEindex of an ePDCCH in CSS could be the same as the eCCE index of anePDCCH in a UESS. Therefore, in some examples, both the search space andthe ePDCCH resource position are used to uniquely identify an ePDCCHwithin the available ePDCCH resources.

Similarly, it is possible that the position of a UE's ePDCCH could bedetermined differently for localized and distributed ePDCCHtransmission. A localized ePDCCH in one PRB could have the same ePDCCHposition as a distributed ePDCCH in another PRB. Therefore, in someexamples, both the ePDCCH allocation type (localized or distributedallocation) and the ePDCCH position are used to uniquely identify anePDCCH within ePDCCH resources.

Both ePDCCH and PDCCH may be present in a subframe. One feature forePDCCH is that ePDCCH resources could be occupied by PDSCH if notscheduled with localized ePDCCH transmission, so ePDCCH overhead couldbe low even though large resources are configured for potential ePDCCHtransmission.

As discussed previously, for most PDSCH transmissions in the downlink toa UE, a corresponding PUCCH resource is needed in the uplink for A/Ntransmission by the UE. This is true also for PDSCH transmissionscheduled by ePDCCH. However, as described above, LTE Rel-10 implicitPUCCH resource allocation was designed based on a one to one mappingbetween PUCCH and PDCCH resources. Thus, using those same techniques toperform PUCCH resource allocation for PDSCHs scheduled by ePDCCHs canlead to several problems. For example, such prior PDCCH techniques forPUCCH resource allocation can yield inefficient PUCCH resources (e.g.,by over-allocating PUCCH resources). Additionally, as discussed above,the starting eCCE index of an ePDCCH may not uniquely identify theePDCCH and thus, the prior PDCCH techniques for PUCCH allocation, whichuse just the starting CCE index to identify the PDCCH, may result inambiguous PUCCH allocations when used with an ePDCCH. For example, inthe case of MU-MIMO transmission, an eCCE index may not uniquelyidentify an ePDCCH and, thus, PUCCH resources determined for a giveneCCE index could be the same for two MU-MIMO users with ePDCCHs in thesame eCCEs. This could lead to different UEs transmitting on the samePUCCH resource, and the inability of the network to decode theirAck/Nack transmission. As another example, because eCCEs in common andUE specific search spaces could be indexed separately, one eCCE indexmay not uniquely identify the location of an ePDCCH in both searchspaces. It may be possible for an ePDCCH in one UE's CSS to have thesame eCCE indices as an ePDCCH in another UE's UESS. If implicitresource allocation used only the eCCE index, as in the case of theprior PDCCH-based techniques of LTE Rel-10, the same PUCCH resourcescould be allocated to both UEs. As yet another example, localized anddistributed ePDCCH may also be indexed separately. If a UE scheduled ona localized ePDCCH and another UE scheduled on a distributed ePDCCH canoccupy eCCEs with the same indices, then determining their PUCCHresources solely from the eCCE index could result in a PUCCH resourcecollision.

Another problem associated with using prior PDCCH-based resourceallocation is that a UE's search space on PDCCH in LTE Release-8 (Rel-8)may be constrained such that higher aggregation level PDCCHs can only bescheduled in a restricted set of CCEs. An aggregation level L PDCCH canonly be scheduled in CCEs that satisfy mod(n_(CCE),L)=0, where n_(CCE)is the location of the PDCCH in the available PDCCH resources.Therefore, some CCEs may be more frequently occupied than others. Morequantitatively, consider an example of L₀=4 CCEs that satisfymod(n_(CCE),4) ∈ {0,1,2,3}. For purposes of discussion, define n_(CCE)≡mod(n_(CCE),4), and refer to a set of CCEs that have n _(CCE)=ias CCE group i. For example, in an urban macro environment, theprobability that aggregation levels 1, 2, 4, and 8 are occupied has beenfound in one example simulation to be 29.8%, 39.4%, 18.1%, and 12.7%,respectively. Aggregation level 1, 2, 4, and 8 PDCCHs can be scheduledin CCEs that satisfy n _(CCE) ∈ {0,1,2,3}, n _(CCE) ∈ {0,2}, n _(CCE) ∈{0}, and n _(CCE) ∈ {0}, respectively. Therefore, assuming that PDCCHsat a given aggregation level are distributed evenly over all thepossible locations, the probability of occupancy in an urban macroenvironment for the CCE groups in the foregoing example is:29.8/4+39.4/2+18.1+12.7=58% for CCE group 0; 29.8/4=7.4% for CCE group1; 29.8/4+39.4/2=27.1% for CCE group 2; and 29.8/4=7.4% for CCE group 3.In such an example, CCE group 0 is 58/7.4=7.8 times more likely to beoccupied than CCE group 1. Unfortunately, because the PUCCH resourcescorresponding to CCE groups are evenly distributed across PUCCHresources, all PRBs in Rel-8 PUCCH resources tend to be occupied. Thismeans it is infeasible to exploit uneven occupancy of CCE groups toimprove PUCCH resource allocation efficiency.

With reference to FIG. 1, the UE UCC resource allocator 125 of the UE105 and the eNB UCC resource allocator 130 of the eNB 110 implement oneor more solutions, or combination(s) thereof, for performing uplinkcontrol channel resource allocation for an enhanced downlink controlchannel, which includes PUCCH resource allocation for an ePDCCH. In atleast some examples, the solution(s) implemented by the UE UCC resourceallocator 125 and the eNB UCC resource allocator 130 can overcome one ormore of the problems associated with PDCCH-based resource allocationtechniques discussed above. Example resource allocation solutions thatcan be implemented by the UE UCC resource allocator 125 and the eNB UCCresource allocator 130 include, but are not limited to, any one or more(or combination) of the following:

A) hybrid implicit/explicit resource allocation, where one or moretables of PUCCH resources corresponding to at least the location of atransmission to a UE on ePDCCH or PDSCH are used for PUCCH resourceallocation;

B) extended implicit resource allocation where PUCCH resources are notsignaled, but instead are directly mapped from the transmission locationof the ePDCCH using UE specific parameters;

C) dynamic signaling of an A/N PUCCH resource region in downlink controlinformation;

D) PUCCH resource remapping, where infrequently occupied CCEs are mappedcloser together in PUCCH resource regions;

E) PUCCH resource allocation using a dynamic PUCCH offset indicationprovided in DCI.

For example, hybrid resource allocation allows arbitrary mapping toPUCCH resources, including mapping a many-to-one ePDCCH resource indexto a PUCCH resource mapping that allows more efficient operation foraggregation levels greater than 1. Also, UE-specific PUCCH resources areavailable, and localized and distributed ePDCCHs can share the samePUCCH resource. However, hybrid resource allocation may increase RRCsignaling overhead.

Extended implicit resource allocation also allows for efficient usage ofPUCCH resources for aggregation levels greater than 1 by using a many toone mapping. Extended implicit resource allocation differs from hybridresource allocation in that it does not utilize explicit signaling ofPUCCH resources. However, because the PUCCH resource allocations aremade different in extended implicit resource allocation by making theinput parameters to the allocation function different, extended implicitresource allocation may utilize more parameters and more complexity tomatch the same level of flexibility as hybrid implicit/explicit resourceallocation.

Dynamic signaling of an A/N PUCCH resource region selects among multiplePUCCH resource regions that are semi-statically configured to a UE. Aregion is selected dynamically through DCI. Within the selected region,a predefined mapping table or function (e.g., such as that associatedwith hybrid resource allocation or extended implicit resourceallocation) can be used to map between an ePDCCH scheduled PDSCH and aPUCCH resource.

PUCCH resource remapping does not use a many to one mapping. Instead, itis based on the realization that the LTE Rel-10 PDCCH search spaceconstraints can result in rather uneven use of PDCCH CCEs. Based on thisrealization, PUCCH resource remapping makes changes to Rel-10 implicitPUCCH resource allocation such that groups of CCEs are mapped to PUCCHresources based on how frequently they are occupied. For example, themost frequently occupied eCCE groups can be mapped to low PUCCH resourceindices, so PUCCH PRBs corresponding to high PUCCH resource indices maybe infrequently occupied, and so a smaller amount of total PUCCHresources may be used.

These and other resource allocation solutions that can be implemented bythe UE UCC resource allocator 125 and the eNB UCC resource allocator 130of FIG. 1 are described in greater detail below in the context of theflowcharts and illustrations provided in FIGS. 5-25. Also, as notedabove, various combinations of the above solutions can be implemented bythe UE UCC resource allocator 125 and the eNB UCC resource allocator130. For example, resource remapping can be performed within eachdynamically signaled resource region by combining dynamic signaling ofan A/N PUCCH resource region (C) with PUCCH resource remapping (D).

While an example manner of implementing the mobile communication system100, the UE device 105, the eNB 110, the UE UCC resource allocator 125and the eNB UCC resource allocator 130 has been illustrated in FIG. 1,one or more of the elements, processes and/or devices illustrated inFIG. 1 may be combined, divided, re-arranged, omitted, eliminated and/orimplemented in any other way. Further, the example mobile communicationsystem 100, the example UE device 105, the example eNB 110, the exampleUE UCC resource allocator 125 and/or the example eNB UCC resourceallocator 130 of FIG. 1 may be implemented by hardware, software,firmware and/or any combination of hardware, software and/or firmware.Thus, for example, any of the example mobile communication system 100,the example UE device 105, the example eNB 110, the example UE UCCresource allocator 125 and/or the example eNB UCC resource allocator 130could be implemented by one or more circuit(s), programmableprocessor(s), application specific integrated circuit(s) (ASIC(s)),programmable logic device(s) (PLD(s)) and/or field programmable logicdevice(s) (FPLD(s)), etc. When any of the apparatus or system claims ofthis patent are read to cover a purely software and/or firmwareimplementation, at least one of the example mobile communication system100, the example UE device 105, the example eNB 110, the example UE UCCresource allocator 125 and/or the example eNB UCC resource allocator 130are hereby expressly defined to include a tangible computer readablemedium such as a memory, digital versatile disk (DVD), compact disk(CD), Blu-ray disc™, etc., storing such software and/or firmware.Further still, the example mobile communication system 100, the exampleUE device 105, the example eNB 110, the example UE UCC resourceallocator 125 and/or the example eNB UCC resource allocator 130 of FIG.1 may include one or more elements, processes and/or devices in additionto, or instead of, those illustrated in FIG. 1, and/or may include morethan one of any or all of the illustrated elements, processes anddevices.

Flowcharts representative of example processes for implementing theexample mobile communication system 100, the example UE device 105, theexample eNB 110, the example UE UCC resource allocator 125 and/or theexample eNB UCC resource allocator 130 of FIG. 1 are shown in FIGS.5-24. In these examples, the process represented by each flowchart maybe implemented by one or more programs comprising machine readableinstructions for execution by a processor, such as the processor 2512shown in the example processing system 2500 discussed below inconnection with FIG. 25. The one or more programs, or portion(s)thereof, may be embodied in software stored on a tangible computerreadable storage medium such as a CD-ROM, a floppy disk, a hard drive, adigital versatile disk (DVD), a Blu-ray disc™, or a memory associatedwith the processor 2512, but the entire program or programs and/orportions thereof could alternatively be executed by a device other thanthe processor 2512 (e.g., such as a controller and/or any other suitabledevice) and/or embodied in firmware or dedicated hardware (e.g.,implemented by an ASIC, a PLD, an FPLD, discrete logic, etc.). Also, oneor more of the processes represented by the flowchart of FIGS. 5-24, orone or more portion(s) thereof, may be implemented manually. Further,although the example processes are described with reference to theflowcharts illustrated in FIGS. 5-24, many other methods of implementingthe 5-24 may alternatively be used. For example, with reference to theflowcharts illustrated in FIGS. 5-24, the order of execution of theblocks may be changed, and/or some of the blocks described may bechanged, eliminated, combined and/or subdivided into multiple blocks.

As mentioned above, the example processes of FIGS. 5-24 may beimplemented using coded instructions (e.g., computer readableinstructions) stored on a tangible computer readable storage medium suchas a hard disk drive, a flash memory, a read-only memory (ROM), a CD, aDVD, a cache, a random-access memory (RAM) and/or any other storagemedia in which information is stored for any duration (e.g., forextended time periods, permanently, brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm tangible computer readable storage medium is expressly defined toinclude any type of computer readable storage device and/or storagedisk, and to exclude propagating signals. Additionally or alternatively,the example processes of FIGS. 5-24 may be implemented using codedinstructions (e.g., computer readable instructions) stored on anon-transitory computer readable medium, such as a flash memory, a ROM,a CD, a DVD, a cache, a random-access memory (RAM) and/or any otherstorage media in which information is stored for any duration (e.g., forextended time periods, permanently, brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm non-transitory computer readable medium is expressly defined toinclude any type of computer readable storage device and/or storagedisk, and to exclude propagating signals. Also, as used herein, theterms “computer readable” and “machine readable” are consideredequivalent unless indicated otherwise. Furthermore, as used herein, whenthe phrase “at least” is used as the transition term in a preamble of aclaim, it is open-ended in the same manner as the term “comprising” isopen ended. Thus, a claim using “at least” as the transition term in itspreamble may include elements in addition to those expressly recited inthe claim.

A first example UE process 500 that may be executed to implement theexample UE UCC resource allocator 125 of FIG. 1 is illustrated in FIG.5. A corresponding first example eNB process 600 that may be executed toimplement the example eNB UCC resource allocator 130 of FIG. 1 isillustrated in FIG. 6. The first example processes 500 and 600 implementa first example solution (also referred to herein as example solution#1) disclosed herein for performing PUCCH resource allocation for anePDCCH. Example solution #1 corresponds to hybrid implicit/explicitallocation using, for example, DMRS and eCCE or PRB indices.Furthermore, the first example processes 500 and 600 can be used toimplement at least two example types of hybrid implicit/explicit PUCCHresource allocation. In the first example type, the resource allocationis not adjusted by the ePDCCH region size, whereas the allocation in thesecond example type is a function of the ePDCCH region size.

For hybrid allocation with a fixed ePDCCH region size, a table of PUCCHresources is signaled by the eNB 110 to the UE 105 and used by the UE105 to determine the PUCCH resources. The resource(s) the UE 105 is totransmit on are determined by selecting the resources from the tableusing at least the position of a downlink transmission to the UE 105,the position having a resource index. For example, the downlinktransmission may be a downlink grant on an ePDCCH, a data transmissionon a PDSCH, etc. In addition to the resource index, a DMRS identifiermay be used to select PUCCH resources, for example when the UE 105receives MU-MIMO ePDCCHs. For example, the DMRS identifier may be anantenna port, a DMRS scrambling index, etc., or it may identify acombination of antenna port and DMRS scrambling index, etc. The tablemay be specific to each UE 105, and may contain different sets of PUCCHresources according to the type of the ePDCCH transmission, where thesets are selected depending on, for example, whether the ePDCCH is in aCSS or a UESS, and/or whether the ePDCCH is distributed or localized.PUCCH resources can be shared between these sets to improve resourceusage efficiency, or the sets may have more disjoint resource usage inorder to decrease the chance of resource assignment collisions,depending on the loading and available PUCCH resource. In some examples,a network 100 using hybrid implicit/explicit allocation may constructthe tables assigned to the UE 105 using techniques similar to those usedfor ARI in LTE Rel-10.

In example solution #1, the use of a table of PUCCH resources is enabledby a disclosed example many-to-one mapping of a normalized resourceindex to a table index that ensures the table index stays within thebounds of the table. In some examples, the normalized resource index iscalculated by dividing the resource index of a downlink control or datatransmission to the UE by its length, and quantizing the dividend to aninteger. In some examples, the many to one mapping may map a sum of thenormalized resource index and a scaled index of a DMRS configuration orantenna port to the table index.

With the foregoing in mind, and with reference to the preceding figuresand associated descriptions, the example process 500 of FIG. 5 beginsexecution at block 505 at which the UE UCC resource allocator 125 of theUE 105 obtains (e.g., via signaling from the eNB 110 and/or any othermanner) any uplink control channel allocation parameters to be used forperforming PUCCH resource allocation. At block 510, the UE UCC resourceallocator 125 obtains (e.g., via signaling from the eNB 110 and/or anyother manner) one or more tables specifying a set of possible PUCCHresources to which the UE 105 may be allocated. At block 515, the UE UCCresource allocator 125 determines a DMRS identifier based on DMRSinformation associated with an ePDCCH transmission to be received by theUE 105. At block 520, the UE 105 receives an ePDCCH transmission forwhich one or more PUCCH resources are to be allocated. At block 525, theUE UCC resource allocator 125 determines a position (e.g., an eCCEindex) of the received ePDCCH transmission.

As described above and in greater detail below, at block 530, the UE UCCresource allocator 125 normalizes the determined position of thereceived ePDCCH transmission to determine a normalized resource index.At block 535, the UE UCC resource allocator 125 processes the normalizedresource index and the DMRS identifier with a mapping function (e.g.,which may be based on the parameters obtained at block 505), asdescribed in greater detail below, to determine a table index into thetable obtained at block 510. At block 540, the UE UCC resource allocator125 uses the table index to select an allocated PUCCH resource from theset of possible PUCCH resources included in the table. Then, at block545, the UE 105 transmits on the allocated PUCCH resource selected fromthe table.

Correspondingly, the example process 600 of FIG. 6 begins execution atblock 605 at which the eNB UCC resource allocator 130 of the eNB 110provides (e.g., via signaling and/or any other appropriate manner) tothe UE 105 any uplink control channel allocation parameters to be usedfor performing PUCCH resource allocation. At block 610, the eNB UCCresource allocator 130 provides (e.g., via signaling and/or any othermanner) one or more tables specifying a set of possible PUCCH resourcesto which the UE 105 may be allocated. At block 615, the eNB 110transmits the ePDCCH for which the one or more PUCCH resources are to beallocated. In some examples, the eNB 110 determines a DMRS port and/or aDMRS scrambling index and the associated DMRS identifier for use intransmitting the ePDCCH. The eNB 110 also determines the position (e.g.an eCCE index) at which it will transmit the ePDCCH. The eNB 110 thentransmits the ePDCCH to the UE 105 at the determined position using theDMRS port and/or the DMRS scrambling index.

An example operation 700 of the example processes 500 and 600implementing example solution #1 in which the position of an ePDCCH ismapped to a PUCCH resource is illustrated in FIG. 7. In the illustratedexample of FIG. 7, a normalized resource index is calculated as └k/L┘,using the index of the first eCCE of a UE's ePDCCH (‘x’) and the lengthof the ePDCCH (‘L’) in units of eCCE, and where └x┘ is the largestinteger smaller than or equal to the real number x. The normalizedresource index └k/L┘ and the ePDCCH's MU-MIMO layer (‘m’) are thencombined and sent to a modulo function to produce a table index. In theillustrated example, the table index calculation is expressed asmod(└k/L┘+Gm,N_(ARI)). In the illustrated example of FIG. 7, the MU-MIMOscale factor, G, and the table size, N_(ARI), are assumed to be G=2 andN_(ARI)=4. The table index is used in the corresponding table for the UEto determine the PUCCH resource allocated for that UE, where ARI_(u,n)_(type) is a table of PUCCH resources specific to UE denoted by u inFIG. 7. The UE's allocated PUCCH resource is shown as n_(PUCCH,UEu) ⁽¹⁾in the FIG. 7.

The example operation 700 illustrated in FIG. 7, which corresponds tothe first type of hybrid implicit/explicit allocation that is notadjusted by the ePDCCH region size, can be modified to support caseswhen, for example, the number of PUCCH resources a UE uses varies. Whenthe number of available ePDCCH resources varies, it may be possible forthe mapped PUCCH resources to exist in one subframe and not in another.Therefore, when the number of PUCCH resources may vary with time, thesecond type of hybrid implicit/explicit allocation, which corresponds tohybrid implicit/explicit allocation that is a function of the ePDCCHregion size, may be used to vary the mapping to ensure that it stayswithin the available PUCCH resources and/or to improve PUCCH resourceutilization efficiency.

For example, PUCCH resource efficiency may be improved by using avariable PUCCH resource scale factor on the PUCCH resource value lookedup from the table. As described in further detail below, the PUCCHresource scale factor can be calculated in each subframe according tothe available PUCCH resource, which allows the mapping to track theavailable PUCCH resource.

Further details concerning example solution #1, which corresponds tohybrid implicit/explicit resource allocation and which may beimplemented by the example processes 500 and/or 600, are now provided.Per the discussion above, two disclosed examples of hybridimplicit/explicit allocation are considered. In the first, the resourceallocation is not adjusted by the ePDCCH region size, whereas theallocation in the second disclosed example is a function of the ePDCCHregion size.

In an example of hybrid PUCCH allocation with a fixed ePDCCH regionsize, which may be implemented by the example processes 500 and/or 600,a table of PUCCH resources is used to determine the PUCCH resources a UE(e.g., the UE 105) is to transmit on. The resources are at leastdetermined by an ePDCCH or a PDSCH resource index. A normalized resourceindex is calculated by dividing the resource index by the length of theePDCCH or PDSCH transmission to the UE, and quantizing the dividend toan integer. The normalized index is used to determine the UE's PUCCHresources from the table. In addition to the resource index, a DMRSidentifier may be used to determine PUCCH resources when a UE canreceive MU-MIMO ePDCCHs. The table may contain different sets of PUCCHresources according to the type of the ePDCCH transmission, where thesets are selected depending on whether the ePDCCH is in CSS or UESS,and/or on whether the ePDCCH is distributed or localized. The PUCCHresource allocation for this example type of solution #1 may bedescribed as a mapping function using the Equation 5 below:

n _(PUCCH) ⁽¹⁾=ARI_(u,n) _(type) (mod(└k/L┘+Gm, N _(ARI)))   Equation 5

Equation 5 includes the following parameters:

n_(PUCCH) ⁽¹⁾ is a vector of one or more PUCCH resources the UE maytransmit on. This vector may contain more than one PUCCH resource whenan LTE UE is configured to transmit PUCCH format 1b with channelselection or when it is configured to transmit PUCCH using transmitdiversity;

ARI_(u,n) _(type) is a table of PUCCH resources for the UE u scheduledon an ePDCCH transmission type indexed by n_(type). ARI_(u,n) _(type)(i) is the i^(th) element of the table, and is a vector of one or morePUCCH resources. Each UE's ARI_(u,n) _(type) contains N_(ARI) elements.For consistency with Rel-10 ARI operation, this value can be N_(ARI)=4when N_(DMRS)=1, where N_(DMRS) is the number of DMRS configurationsused for the ePDCCH or the corresponding PDSCH. Otherwise (e.g., whenN_(DMRS)≠1), this value can be larger, and may be for exampleN_(ARI)=4N_(DMRS);

u is an integer index representing a particular UE;

n_(type) is an integer representing the ePDCCH transmission type. It mayhave different values when ePDCCH is transmitted on CSS than when it istransmitted on UESS, and/or than when ePDCCH is localized, and/or thanwhen ePDCCH is distributed;

k is an integer that identifies a location of ePDCCH containing adownlink grant to the UE, or that identifies the location of a PDSCHtransmission containing data for the UE;

L is the length of the ePDCCH in eCCEs or the PDSCH transmission inPRBs;

└k/L┘ is a normalized resource index;

m is an integer that identifies an antenna port and/or an MU-MIMO layerof an ePDCCH containing a downlink grant to the UE. If m is not needed(such as when MU-MIMO is not used on ePDCCH), it can be omitted, orequivalently set to 0;

G is an integer used to allow ePDCCHs on different antenna ports and/orMU-MIMO layers to be mapped farther apart in PUCCH resources. It can beomitted (equivalently set G=1) if not needed;

└x┘ is the largest integer smaller than or equal to the real number x;

mod(x, y) is the remainder when the integer x is divided by the integery. When x and y are vectors, they are the same size, and the calculationis done element by element. That is, the remainder of x(i) divided byy(i) is calculated where 1≦i≦I and I is the maximum index of vector x.

In a first disclosed example of hybrid implicit/explicit allocation, aPUCCH resource is determined using the resource position and the DMRSconfiguration of the ePDCCH transmitted to the UE. In this case,k=n_(eCCE), where n_(eCCE) is the location of the ePDCCH in ePDCCHresources. It may be an index of one of the eCCEs (such as the firstCCE) of the ePDCCH transmitted to the UE. The value of m is set tom=n_(DMRS). The variable n_(DMRS) is an index of a DMRS configurationused in a successful decode of a ePDCCH located at n_(eCCE). Each DMRSconfiguration can be a combination of scrambling index and antenna port.It is possible that the combinations of scrambling index and/or antennaport could be fixed in one or more future LTE specifications, and/orsignaled with radio resource control (RRC) signaling, and that either orboth of the scrambling index or antenna port could be fixed to a singlevalue for a UE. N_(DMRS) is the number of DMRS configurations of theePDCCH DMRS(s) that may be a phase reference for the ePDCCH. Also,G=┌N_(ARI)/N_(DMRS)┐, where ┌x┐ is the smallest integer greater than orequal to the real number x.

An example operation 800 of this first disclosed example of hybridimplicit/explicit PUCCH resource allocation is illustrated in FIG. 8.The X axis of FIG. 8 shows the eCCEs that are occupied by the UEs'ePDCCHs, while the Y axis of FIG. 8 shows the DMRS configuration onwhich they are transmitted. FIG. 8 shows the case where the DMRSconfiguration corresponds to an MU-MIMO layer. The eCCE locations aregiven as the eCCE index, n_(eCCE), and the MIMO layer is indexedaccording to the DMRS configuration associated with that layer,n_(DMRS). In the illustrated example operation 800 of FIG. 8, five UEsare scheduled on ePDCCH. Considering the first three UEs, UE1 and UE3are both scheduled using MU-MIMO, occupying the same eCCEs but ondifferent MU-MIMO layers (e.g., eCCEs 0 and 1 on MU-MIMO layers 0 and 1in the example operation 800 of FIG. 8), whereas UE2 is scheduled in adifferent set of eCCEs (e.g., eCCEs 4 and 5 in the example operation 800of FIG. 8). The PUCCH resource associated with the ePDCCH for UE1, 2,and 3 are labeled in FIG. 8 as n_(PUCCH,UE1) ⁽¹⁾, n_(PUCCH,UE2) ⁽¹⁾, andn_(PUCCH,UE3) ⁽¹⁾, respectively.

In the example operation 800, the PUCCH resources for the UEs aredetermined by substituting the corresponding values of n_(eCCE) andn_(DMRS) for each UE. Considering a disclosed example where n_(eCCE) isdetermined as the index of the first eCCE index occupied by the ePDCCH,then for UE2, n_(eCCE)=4 and n_(DMRS)=0. If N_(DMRS)=4,N_(ARI)=4N_(DMRS)=16, and G=N_(ARI)/N_(DMRS)=4, then since UE2's ePDCCHoccupies two eCCEs, L=2, and n_(PUCCH,UE2) ⁽¹⁾=ARI_(2,n) _(type)(mod(└4/2┘+4·0,16))=ARI_(2,n) _(type) (2), where x·y indicates that xand y are multiplied together. Similarly, the PUCCH resources for UEs 1and 3 are determined as n_(PUCCH,UE1) ⁽¹⁾=ARI_(1,n) _(type)(mod(└0/2┘+4·0,16))=ARI_(1,n) _(type) (0), and n_(PUCCH,UE)⁽¹⁾=ARI_(3,n) _(type) (mod(└0/2┘+4·1,16))=ARI_(3,n) _(type) (4),respectively. Therefore it can be seen that if ARI_(1,n) _(type)(0)≠ARI_(2,n) _(type) (2)≠ARI_(3,n) _(type) (4), then all three UEs willbe assigned distinct PUCCH resources, as is needed for correct Ack/Nackoperation,

UEs 1 and 2 show the benefit of using the position of the ePDCCH inePDCCH resources to determine PUCCH resource. Because UEs 1 and 2 occupydifferent eCCEs, and so have different values of n_(eCCE), the firstvalue (with index 0) of ARI₁ and the third value (with index 2) of ARI₂,respectively, are allocated to UEs 1 and 2. Therefore, moving theePDCCHs in ePDCCH resources results in different PUCCH resourceassignments. This allows the network to control PUCCH resourceassignment by selecting where UEs' ePDCCHs are scheduled in ePDCCHresources.

A possible benefit of using a normalized PUCCH resource index is thatmore values of the ARI function can be produced when L>1. If theresource index is not normalized, then Equation 5 would instead be:

n _(PUCCH) ⁽¹⁾=ARI_(u,n) _(type) (mod(k+Gm, N _(ARI)))   Equation 6

The LTE Rel-10 PDCCH search space is constructed such that PDCCHs starton even boundaries of aggregation levels, such that mod(n_(CCE),L)=0.Assuming that ePDCCH has the same behavior, then with k=n_(eCCE), wehave rem(k,L)=0. For example, if L=N_(ARI)=4 and m=0, then Equation 6becomes n_(PUCCH) ⁽¹⁾=ARI_(u,n) _(type) (mod(k,4))=ARI_(u,n) _(type)(0). Therefore, only one value of ARI( ) would be produced in this case.However, if Equation 5 is used instead, then four (4) distinct values ofARI( ) are possible, since if 0≦k<16, then mod(└k/L┘,4) ∈ {0,1,2,3}.Therefore, it can be observed that the normalization can allow betterscheduling flexibility for higher aggregation levels.

In the example operation 800 of FIG. 8, UEs 1 and 3 show the benefit ofusing n_(DMRS) to determine PUCCH resource. If the ARI function weredefined without it, the definition could be n_(PUCCH) ⁽¹⁾=ARI_(u,n)_(type) (mod(└k/L┘,N_(ARI))) and the assigned PUCCH resources would thenbe n_(PUCCH,UE1) ⁽¹⁾=ARI_(1,n) _(type) (mod(└0/4┘,16))=ARI_(1,n) _(type)(0) and n_(PUCCH,UE3) ⁽¹⁾=ARI_(3,n) _(type) (mod(└0/4┘,16))=ARI_(3,n)_(type) (0). If ARI₁(0)=ARI₃(0) the same PUCCH resources would beassigned to UEs 1 and 3, resulting in incorrect Ack/Nack operation.However, when n_(DMRS) is used in the ARI functions, different indicesare used to look up each UE's PUCCH resource(s), and the network hasbetter control over how PUCCH resources are allocated. Stated anotherway, because n_(eCCE) and n_(DMRS) can be independent variables that areboth dynamic and under network control, the using them both to determinethe PUCCH resources allows the scheduler more flexibility to optimallyschedule ePDCCH while avoiding PUCCH resource conflicts.

UEs 4 and 5 in the example operation 800 of FIG. 8 have somewhatdifferent behavior than the first 3 UEs. UEs 4 and 5 are both scheduledon MU-MIMO layer 2, and are assigned PUCCH resources n_(PUCCH,UE4)⁽¹⁾=ARI_(4,n) _(type) (mod(└2/2┘+4·2,16))=ARI_(4,n) _(type) (9) andn_(PUCCH,UE5) ⁽¹⁾=ARI_(5,n) _(type) (mod(└4/4┘+4·2,16))=ARI_(5,n)_(type) (9), respectively. The arguments in the ARI( ) functions for UEs1-3 were distinct, and so in that case it would be possible to have oneset of values for ARI, such that ARI_(1,n) _(type) (i)=ARI_(2,n) _(type)(i)=ARI_(3,n) _(type) (i) for all values of i. However, if one set ofvalues for ARI were used for UEs 4 and 5, then the PUCCH resources wouldbe n_(PUCCH,UE4) ⁽¹⁾=ARI_(4,n) _(type) (9)=ARI_(5,n) _(type)(9)=n_(PUCCH,UE5) ⁽¹⁾. Incorrect Ack/Nack operation would result fromusing the same PUCCH resources for UEs 4 and 5. Therefore, UEs 4 and 5illustrate the benefit of using different PUCCH resources between UEs'ARI( ) functions.

It may be desirable to identify ePDCCH transmissions using the DMRS portthey are transmitted on instead of the more general DMRS configurationindex defined in the example of Equation 5. Therefore, in anotheralternate disclosed example of hybrid implicit/explicit allocation,m=p−7, where p ∈ {7,8,9,10} is a DMRS port that at least a portion ofthe ePDCCH is transmitted to the UE on.

Since a PUCCH ACK/NACK transmission is in response to a PDSCHtransmission, some examples of hybrid implicit/explicit PUCCH resourceallocation use PDSCH parameters rather than parameters of an ePDCCHscheduling the PDSCH transmission. Such example techniques may beappropriate for subframes where all PDSCHs are scheduled by ePDCCH andthere is no PDCCH on a carrier. Subframes of the so called ‘New CarrierType’ (NCT) discussed for LTE Rel-11 standards could have suchconfiguration. Therefore, in another alternate disclosed example ofhybrid implicit/explicit allocation, k=n_(PDSCH), where n_(PDSCH) is thelocation of the PDSCH in PDSCH resources. It may be an index of one ofthe PDSCH PRBs (such as the first PRB) of the PDSCH transmission. Insuch examples, m can be set to m=n_(DMRS), but with n_(DMRS) defined tobe an index of a DMRS configuration used to decode a PDSCH located atn_(PDSCH). Each DMRS configuration can be a combination of scramblingindex and antenna port. It is possible that the combinations ofscrambling index or antenna port could be fixed in specifications orsignaled with RRC signaling, and that either or both of the scramblingindex or antenna port would be fixed to a single value for a UE.N_(DMRS) is the number of DMRS configurations of the PDSCH DMRS(s) thatmay be phase reference(s) for the PDSCH. Also,G=┌N_(ARI)/N_(DMRS┐, where ┌x┐ is the smallest integer greater than or equal to the real number x.)

As described above, the position of an ePDCCH in ePDCCH resources maynot be unique unless the search space or allocation type is taken intoaccount. Therefore, different sets of resources for ARI( ) may be usedby the UE for localized allocations than for distributed allocations. Inother words, assuming n_(type)=1 for localized allocation and n_(type)=2for distributed allocation, then ARI_(u,1)(i)≠ARI_(u,2)(i) in someexamples.

In some examples, a set of PUCCH resources for ARI( ) may be shared bymultiple UEs for ePDCCHs in a common search space. In such examples, itcan be beneficial to broadcast the list to all UEs served by a cell in amessage on a common control channel, such as a system information block(SIB), using an RRC message with a group based radio network temporaryidentifier (RNTI) on an ePDCCH transmitted to a group of UEs in a cell,or to specify predetermined values of the list such that they are knownto both the network and UE (e.g. by including the values of the list inphysical layer specifications). The lists of PUCCH resourcescorresponding to UE specific search spaces or localized ePDCCH may bedifferent for each UE, and so may be signaled to each UE independentlyusing dedicated messaging, e.g. via RRC signaling. The parameter G canbe either broadcast in SIB or signaled to each UE individually throughdedicated signaling.

The disclosed example defined by Equation 5 above maps PUCCH resourceallocations to a fixed set of PUCCH resources. If the number of PUCCHresources varies with time, which can be desirable when the number ofavailable ePDCCH resources varies subframe by subframe, such as thatcontrolled by a new enhanced physical control channel format indicatorchannel (ePCFICH) control, it would be possible for the mapped PUCCHresources to exist in one subframe and not in another. Therefore, whenthe number of PUCCH resources may vary with time, a second disclosedexample may be used that varies the mapping as a function of the ePDCCHregion size to ensure that it stays within the available PUCCHresources. This second disclosed example, which may be implemented bythe example processes 500 and/or 600, can be described as a mappingfunction using Equation 7 below.

n _(PUCCH) ⁽¹⁾=└ARI_(u)(mod(└k/L┘+Gm,N _(ARI)))·E _(Δ) ┘+N _(ePUCCH)⁽¹⁾(u,n _(type))   Equation 7

In Equation 7, the variables as defined for Equation 5 are the same, andEquation 7 also includes the following parameters:

ARI_(u)(i) is a list of PUCCH resource vectors for the UE with index u,indexed by the integer i. ARI_(u)(i) contains N_(ARI) elements. Thisvalue can be N_(ARI)=4 when N_(DMRS)=1; otherwise this value can belarger, such as, for example, N_(ARI)=4N_(DMRS);

E_(Δ) is a PUCCH resource scale factor determined in each subframe,where 0<E_(Δ)≦1. When ARI_(u,n) _(type) (i) contains more than oneelement, each element of ARI_(u,n) _(type) (i) may be multiplied byE_(Δ). If E_(Δ) is not needed, it can be omitted, or equivalently set to1;

N_(ePUCCH) ⁽¹⁾(u,n_(type)) is a an integer PUCCH resource offset thatdefines the start of PUCCH resources for ePDCCH for a UE with index uscheduled on an ePDCCH transmission type indexed by n_(type). It issimilar to N_(PUCCH) ⁽¹⁾ that is used for PDCCH reception in LTE Rel-8.It may be common to all UEs on the carrier containing ePDCCH, dependingon the ePDCCH transmission type. In such an example, a single value ofN_(PUCCH) ⁽¹⁾(u,n_(type)) can be used for all UEs, that is, N_(ePUCCH)⁽¹⁾(u,n_(type))=N_(ePUCCH) ⁽¹⁾(0,n_(type)) for all UE indices u. IfN_(ePUCCH) ⁽¹⁾(u,n_(type)) may be different for each UE, it may besignaled to UEs with RRC signaling.

The simplifications used for the disclosed example of Equation 5 alsoapply to this disclosed example of Equation 7. If m is not needed (suchas when MU-MIMO is not used on ePDCCH), it can be omitted, orequivalently set to m=0. Also, G can be omitted (equivalently set G=1)if not needed.

The disclosed example of Equation 7 modifies the PUCCH resources thatwould have been allocated by the disclosed example of Equation 5,scaling them by E_(Δ), which can vary with the available PUCCH resourcesin each subframe. A first example way to determine E_(Δ) is to use aformula fixed in future LTE specifications. One way to do this is toselect E_(Δ)=N′_(ePUCCH)/N_(ePUCCH) ^(max), where N′_(ePUCCH) is thetotal number of PUCCH resources required for ePDCCH in a subframe, andN_(PUCCH) ^(max) is the maximum total number of PUCCH resourcesavailable for ePDCCH in any subframe. For example, if ePCFICH issupported, N_(ePUCCH) ^(max) and a list of the values of N′_(ePUCCH)corresponding to the size of ePDCCH are signaled to the UE (e.g., the UE105) using higher layer signaling. In each subframe, the UE looks up thevalue of N′_(ePUCCH) from the list of values of N′_(ePUCCH) by selectingone that corresponds to the size of ePDCCH signaled on ePCFICH.

A second set of example methods to determine E_(Δ) is to use higherlayer signaling in a more direct manner. In one such example method,E_(Δ) is selected from a list of C values indicated to the UE using RRCsignaling or on a system information block (SIB) transmitted using aphysical broadcast channel (PBCH). An element with index c is selectedfrom the list, where c is a positive integer corresponding to the sizeof an ePDCCH region. The index c is indicated to the UE in eachsubframe.

Scaling ARI_(u)(i) by E_(Δ) produces numbers closer to zero independentof the value of u, that is, for all UEs. Therefore, the offsetN_(ePUCCH) ⁽¹⁾(u,n_(type)) is used to allow the PUCCH resource region tobe set independently on a per UE basis. Because N_(ePUCCH)⁽¹⁾(u,n_(type)) can adjust the PUCCH resource region according to theePDCCH transmission type, it is not necessary for ARI_(u)(i) to dependon the transmission type in this disclosed example of hybrid PUCCHallocation that is a function of the ePDCCH region size.

A second example UE process 900 that may be executed to implement theexample UE UCC resource allocator 125 of FIG. 1 is illustrated in FIG.9. A corresponding second example eNB process 1000 that may be executedto implement the example eNB UCC resource allocator 130 of FIG. 1 isillustrated in FIG. 10. The second example processes 900 and 1000implement a second example solution (also referred to herein as examplesolution #2) disclosed herein for performing PUCCH resource allocationfor an ePDCCH. Example solution #2 corresponds to extended implicitresource allocation in which PUCCH resources are not determined (e.g.,indirectly) from lists or tables, but instead are mapped from thereceived ePDCCH transmission location using UE specific parameters.Furthermore, the second example processes 900 and 1000 can be used toimplement at two example types of extended implicit PUCCH resourceallocation. In the first example type, one PUCCH resource is allocated,whereas in the second example type, more than one PUCCH resource isallocated. The latter disclosed example may be used, for example, whenPUCCH format 1b channel selection or PUCCH transmit diversity isconfigured for a UE.

In a disclosed example of extended implicit resource allocation for onePUCCH resource (e.g., the first example type of extended implicitresource allocation), PUCCH resources are directly mapped fromimplicitly signaled parameters rather than being indirectly determinedfrom lists or tables. As in hybrid implicit/explicit resource allocation(e.g., solution #1 discussed above), PUCCH resources are at leastdetermined by a resource index, and a DMRS identifier may be furtherused to determine the PUCCH resources. Different sets of PUCCH resourcesmay be allocated to each UE according to, for example, the type of theePDCCH transmission, with the sets being selected depending on, forexample, whether ePDCCH is in CSS or UESS, and/or on whether ePDCCH isdistributed or localized, etc.

Like hybrid implicit/explicit resource allocation, extended implicitPUCCH resource allocation also uses a many-to-one mapping of anormalized resource index. For example, the normalized resource indexcan be calculated the same way as for hybrid implicit/explicitallocation. In some examples, the normalized resource index can then bemapped to a PUCCH resource by adding a PUCCH resource offset to thenormalized resource index. In some examples, the PUCCH resource offsetmay be signaled to each UE, and different offsets may be signaled forthe different ePDCCH transmission types, such as corresponding towhether ePDCCH is in CSS or UESS, and/or whether ePDCCH is distributedor localized.

If UEs have the same value of a normalized PUCCH resource, as can happenfor ePDCCH MU-MIMO transmission, additional mechanisms may be used toavoid mapping the UEs to the same PUCCH resource when performingextended implicit PUCCH resource allocation. For example, themany-to-one mapping may map a sum of the normalized resource index and ascaled index of a DMRS configuration or antenna port to the PUCCHresource.

It may be desirable to ensure the allocated resources stay withincertain bounds when performing extended implicit PUCCH resourceallocation. For example, the many-to-one mapping may additionallycomprise a modulo division of the normalized resource index or the sumof the normalized resource index with the scaled DMRS configurationindex by a number of available PUCCH resources. In such examples, thePUCCH resource to be used by the UE may be determined by adding thePUCCH resource offset to the result of the modulo division.

With the foregoing in mind, and with reference to the preceding figuresand associated descriptions, the example process 900 of FIG. 9 beginsexecution at block 905 at which the UE UCC resource allocator 125 of theUE 105 obtains (e.g., via signaling from the eNB 110 and/or any othermanner) any uplink control channel allocation parameters to be used forperforming PUCCH resource allocation. At block 910, the UE UCC resourceallocator 125 obtains (e.g., via signaling from the eNB 110 and/or anyother manner) an uplink control channel offset to be used for extendedimplicit PUCCH resource allocation. At block 915, the UE UCC resourceallocator 125 determines a DMRS identifier based on DMRS informationassociated with an ePDCCH transmission to be received by the UE 105. Atblock 920, the UE 105 receives an ePDCCH transmission for which one ormore PUCCH resources are to be allocated. At block 925, the UE UCCresource allocator 125 determines a position (e.g., an eCCE index) ofthe received ePDCCH transmission.

As described above and in greater detail below, at block 930, the UE UCCresource allocator 125 normalizes the determined position of thereceived ePDCCH transmission to determine a normalized resource index.At block 935, the UE UCC resource allocator 125 processes the normalizedresource index, the DMRS identifier and the uplink control channeloffset with a mapping function (e.g., which may be based on theparameters obtained at block 905), as described in greater detail below,to determine an allocated PUCCH resource. At block 940, the UE 105transmits on the allocated PUCCH resource.

Correspondingly, the example process 1000 of FIG. 10 begins execution atblock 1005 at which the eNB UCC resource allocator 130 of the eNB 110provides (e.g., via signaling and/or any other appropriate manner) tothe UE 105 any uplink control channel allocation parameters to be usedfor performing PUCCH resource allocation. At block 1010, the eNB UCCresource allocator 130 provides (e.g., via signaling and/or any othermanner) the uplink control channel offset to the UE 105 for use by theUE 105 when performing extended implicit PUCCH resource allocation. Atblock 1015, the eNB 110 transmits the ePDCCH for which the one or morePUCCH resources are to be allocated. In some examples, the eNB 110determines a DMRS port and/or a DMRS scrambling index and the associatedDMRS identifier for use in transmitting the ePDCCH. The eNB 110 alsodetermines the position (e.g. an eCCE index) at which it will transmitthe ePDCCH. The eNB 110 then transmits the ePDCCH to the UE 105 at thedetermined position using the DMRS port and/or the DMRS scramblingindex.

An example operation 1100 of the example processes 900 and 1000implementing example solution #2 in which the position of an ePDCCH ismapped to a PUCCH resource using extended implicit resource allocationis illustrated in FIG. 11. In the illustrated example of FIG. 11, andlike in hybrid implicit/explicit allocation (e.g., example solution #1),a normalized resource index is calculated as └k/L┘, using the index ofthe first eCCE of a UE's ePDCCH (‘k’) and the length of the ePDCCH (‘L’)in units of eCCE. The normalized resource index └k/L┘ and the ePDCCH'sMU-MIMO layer (‘m’) are then combined and sent to a modulo function thatlimits the combined PUCCH resource to a range. This calculation of thelimited combined PUCCH resource can be expressed as mod(└k/L┘+Gm,N′_(ePUCCH)). In the illustrated example operation 1100 of FIG. 11, theMU-MIMO scale factor, G, is assumed to be G=2. Furthermore, the numberof PUCCH resources available, N′_(ePUCCH) is assumed to be larger thanthe sum of the normalized resource index and scaled MU-MIMO layer index.In the illustrated example operation 1100, the limited combined PUCCHresource is then further combined with a PUCCH resource offset,N_(ePUCCH) ⁽¹⁾(u,n_(type)), to produce the allocated PUCCH resource,where u is the index of the UE and n_(type) is an integer representingthe ePDCCH transmission type (e.g., common search space vs. UE-specificsearch space). The allocated PUCCH resource is for UE u is indicated asn_(PUCCH,UEu) ⁽¹⁾ in the illustrated example operation 1100 of FIG. 11.

The example operation 1100 illustrated in FIG. 11, which corresponds tothe first type of extended implicit PUCCH resource allocation in whichone PUCCH resource is allocated, can be modified to support, forexample, channel selection and/or transmit diversity. When an LTE UE isconfigured to transmit PUCCH format 1b with channel selection or when itis configured to transmit PUCCH using transmit diversity, the UE may beallocated multiple PUCCH resources. Accordingly, in a second exampletype of extended implicit resource allocation, multiple PUCCH resourcesare allocated to a UE.

In some such examples, additional PUCCH resources may be allocated usingextended implicit resource allocation by using secondary PUCCH resourceoffsets. For example, a sum of the secondary PUCCH resource offsets andthe normalized PUCCH resource index may replace the normalized PUCCHresource index that was used in the first type of extended implicitresource allocation calculations for determining one PUCCH resourcecalculation. Furthermore, in some examples, the secondary PUCCH resourceoffsets may be scaled to avoid resource allocation conflicts between UEswith the same normalized PUCCH resources. In other examples, thenormalized PUCCH resource may be replaced by a sum of the secondaryPUCCH offset and a scaled value of the normalized PUCCH resource toavoid the conflicts.

In time division duplex (TDD) operation, a UE (e.g., the UE 105) mayreceive an ePDCCH in each of multiple subframes. In such examples, itmay be desirable for the amount of required PUCCH resources to grow withboth the number of PUCCH resources allocated to a UE in a subframe, aswell as the size of the ePDCCH region. In that way, the amount of PUCCHresource can be reduced when a UE is scheduled fewer PDSCHs and whenfewer UEs are scheduled in a subframe. Therefore, some examples of thesecond type of extended implicit resource allocation allocate higherPUCCH resource indices for UEs scheduled with higher normalized PUCCHresources, and for the PDSCHs with higher time indices, using a timevarying PUCCH resource offset.

Further details concerning example solution #2, which corresponds tohybrid extended implicit resource allocation and which may beimplemented by the example processes 900 and/or 1000, are now provided.Per the discussion above, two disclosed examples for extended implicitresource allocation are considered. The first allocates one PUCCHresource, whereas the second allocates more than one. The latterdisclosed example may be used when PUCCH format 1b with channelselection or PUCCH transmit diversity is configured for a UE (e.g., theUE 105).

In an example of extended implicit resource allocation for one PUCCHresource, PUCCH resources are directly mapped from implicitly signaledparameters rather being indirectly determined from lists or tables. Asin the hybrid implicit/explicit example solution #1 described above, thePUCCH resources are at least determined by a normalized resource index,and a DMRS identifier may be used to determine PUCCH resources when a UEcan receive MU-MIMO ePDCCHs. Different sets of PUCCH resources may beallocated according to the type of the ePDCCH transmission, with thesets being selected depending on, for example, whether ePDCCH is in CSSor UESS, and/or on whether ePDCCH is distributed or localized, etc. Thegeneral form of the extended implicit resource allocation mapping may bedescribed as a mapping function using the equation below:

n _(PUCCH) ⁽¹⁾=mod(└k/L┘+Gm,N′ _(ePUCCH))+N _(ePUCCH) ⁽¹⁾(u,n _(type))  Equation 8

Equation 8 includes the following parameters:

n_(PUCCH) ⁽¹⁾ is a PUCCH resource the UE may transmit on;

k is an integer that identifies the location of an ePDCCH containing adownlink grant to the UE, or that identifies the location of a PDSCHtransmission containing data for the UE;

L is the length of the ePDCCH in eCCEs, or the PDSCH transmission inPRBs;

└k/L┘ is a normalized resource index;

m is an integer that identifies an antenna port and/or an MU-MIMO layerof an ePDCCH containing a downlink grant to the UE. If m is not needed(such as when MU-MIMO is not used on ePDCCH), it can be omitted, orequivalently set to 0;

G is an integer used to allow E-PDCCHs on different antenna ports and/orMU-MIMO layers to be mapped farther apart in PUCCH resources. It can beomitted (equivalently set G=1) if not needed;

N_(PUCCH) ⁽¹⁾(u,n_(type)) is an integer PUCCH resource offset thatdefines the start of PUCCH resources for ePDCCH for a UE with index uscheduled on an ePDCCH transmission type indexed by n_(type). It may besimilar to N_(PUCCH) ⁽¹⁾ that is used for PDCCH reception in LTE Rel-8.In some examples, the integer PUCCH resource offset may be common to allUEs on the carrier containing ePDCCH, depending on the ePDCCHtransmission type. In such examples, a single value of N_(ePUCCH)⁽¹⁾(u,n_(type)) may be used for all UEs, that is, N_(ePUCCH)⁽¹⁾(u,n_(type))=N_(ePUCCH) ⁽¹⁾(0,n_(type)) for all UE indices u. IfN_(ePUCCH) ⁽¹⁾(u,n_(type)) may be different for each UE, it may besignaled to UEs with UE specific RRC signaling;

N′_(ePUCCH) is the number of PUCCH resources available and/or orconfigured for ePDCCH for at least one UE in a subframe;

n_(type) is an integer representing the ePDCCH transmission type. It mayhave different values when ePDCCH is transmitted on CSS than when it istransmitted on UESS, and/or than when ePDCCH is localized, and/or thanwhen ePDCCH is distributed.

mod(x, y) is the remainder when the integer x is divided by the integery.

In a first disclosed example of extended implicit resource allocation, aPUCCH resource is determined using the position and the DMRSconfiguration of the ePDCCH transmitted to the UE. In such an example,k=n_(eCCE), where n_(eCCE) is the location of the ePDCCH in ePDCCHresources. It may be an index of one of the eCCEs (such as the firstCCE) of the ePDCCH transmitted to the UE. Also m=n_(DMRS), wheren_(DMRS) is the DMRS configuration index defined in the disclosedexample of Equation 5.

The operation of this first disclosed example of extended implicit PUCCHresource allocation when G=1 can be demonstrated using the illustrationof FIG. 11 (which was also used for illustrating operation of hybridimplicit/explicit PUCCH resource). In this example, the PUCCH resourcesfor the UEs are determined by substituting the corresponding values of kand m for each UE. Considering a disclosed example where n_(eCCE) isdetermined as the index of the first eCCE index occupied by the ePDCCH,then for UE2 of FIG. 11, u=2, n_(eCCE)=4 and n_(DMRS)=0. If N_(ePUCCH)⁽¹⁾(1,n_(type))=0 and N′_(PUCCH)=16, then since UE2's ePDCCH occupiestwo eCCEs, L=2, and n_(PUCCH,UE2) ⁽¹⁾=mod(└4/2┘+0,16)+N_(ePUCCH)⁽¹⁾(2,n_(type))=2+N_(ePUCCH) ⁽¹⁾(2,n_(type)). Similarly, the PUCCHresources for UEs 1 and 3 of FIG. 1 can be determined as n_(PUCCH,UE1)⁽¹⁾=mod(└0/2┘+1,16)+N_(ePUCCH) ⁽¹⁾(1,n_(type))=N_(ePUCCH)⁽¹⁾(1,n_(type)), and n_(PUCCH,UE3) ⁽¹⁾=mod(└0/2┘+1,16)+N_(ePUCCH)⁽¹⁾(1,n_(type))=1+N_(ePUCCH) ⁽¹⁾(3,n_(type)), respectively. Therefore,it can be seen that if their UE specific offsets are identical, that is,N_(ePUCCH) ⁽¹⁾(1,n_(type))=N_(ePUCCH) ⁽¹⁾(2,n_(type))=N_(ePUCCH)⁽¹⁾(3,n_(type)), then all three UEs 1, 2 and 3 of FIG. 11 will beassigned distinct PUCCH resources, as is needed for correct Ack/Nackoperation.

UEs 1 and 2 of FIG. 11 demonstrate the benefit of using k to determinePUCCH resources. Because UEs 1 and 2 occupy different eCCEs, and so havedifferent values of n_(eCCE), different PUCCH resources are allocated toUEs 1 and 2 even if the UEs' UE specific offsets are identical.Therefore, moving the ePDCCHs in ePDCCH resource results in differentPUCCH resource assignments. This allows the network to control PUCCHresource assignment by selecting where UEs' ePDCCHs are scheduled inePDCCH resources.

UEs 1 and 3 of FIG. 11 demonstrate the benefit of using m to determinePUCCH resource. If the function of Equation 8 was defined without it,the definition could be n_(PUCCH) ⁽¹⁾=mod(└k/L┘,N′_(ePUCCH))+N_(ePUCCH)⁽¹⁾(u,n_(type)), and the assigned PUCCH resources would then ben_(PUCCH,UE1) ⁽¹⁾=mod(└0/2┘,16)+N_(ePUCCH) ⁽¹⁾(1,n_(type))=N_(ePUCCH)⁽¹⁾(1,n_(type)) and n_(PUCCH,UE3) ⁽¹⁾=mod(└0/2┘,16)+N_(ePUCCH)⁽¹⁾(3,n_(type))=N_(ePUCCH) ⁽¹⁾(3,n_(type)). If N_(ePUCCH)⁽¹⁾(1,n_(type))=N_(ePUCCH) ⁽¹⁾(3,n_(type)), the same PUCCH resourceswould be assigned to UEs 1 and 3, resulting in incorrect Ack/Nackoperation. However, when m is used in Equation 8, different indices areused to look up each UE's PUCCH resource(s), and the network has bettercontrol over how PUCCH resources are allocated. Stated another way,because k and m can be independent variables that are both dynamic andunder network control, then using them both to determine the PUCCHresources allows the scheduler more flexibility to optimally scheduleePDCCH while avoiding PUCCH resource conflicts.

UEs 4 and 5 of FIG. 11 have somewhat different behavior than the firstthree UEs 1, 2 and 3. For example, UEs 4 and 5 of FIG. 11 are bothscheduled on MU-MIMO layer 2, and are assigned PUCCH resourcesn_(PUCCH,UE4) ⁽¹⁾=mod(└2/2┘+2,16)+N_(ePUCCH)⁽¹⁾(4,n_(type))=3+N_(ePUCCH) ⁽¹⁾(4,n_(type)) and n_(PUCCH,UE4)⁽¹⁾=mod(└4/4┘+2,16)+N_(ePUCCH) ⁽¹⁾(5,n_(type))=3+N_(ePUCCH)⁽¹⁾(5,n_(type)), respectively. The PUCCH resources for UEs 1-3 weredistinct even when their UE specific offsets were the same, that is,when N_(ePUCCH) ⁽¹⁾(1,n_(type))=N_(ePUCCH) ⁽¹⁾(2,n_(type))=N_(ePUCCH)⁽¹⁾(3,n_(type)). However, if UEs 4 and 5 had the same UE specificoffsets, that is, N_(ePUCCH) ⁽¹⁾(3,n_(type))=N_(ePUCCH) ⁽¹⁾(5,n_(type)),then the PUCCH resources would be n_(PUCCH,UE4) ⁽¹⁾=3+N_(ePUCCH)⁽¹⁾(4,n_(type))=3+N_(ePUCCH) ⁽¹⁾(5,n_(type))=n_(PUCCH,UE5) ⁽¹⁾.Incorrect Ack/Nack operation would result from using the same PUCCHresources for UEs 4 and 5. Therefore, UEs 4 and 5 illustrate the benefitof using different UE specific PUCCH resource offsets in Equation 8,such as when N_(ePUCCH) ⁽¹⁾(4,n_(type))≠N_(ePUCCH) ⁽¹⁾(5,n_(type)).

As described above, the position of an ePDCCH in ePDCCH resources maynot be unique unless the search space or allocation type is taken intoaccount. Therefore, the UE specific PUCCH resource offsets N_(ePUCCH)⁽¹⁾(u,n_(type)) for a given UE may be different for localized allocationand distributed allocation. In other words, assuming n_(type)=1 forlocalized allocation and n_(type)=2 for distributed allocation,N_(ePUCCH) ⁽¹⁾(u,1)≠N_(ePUCCH) ⁽¹⁾(u,2) in some examples.

In addition to UE specific PUCCH resource offsets, common PUCCH resourceoffsets may be used. Common PUCCH resource offsets are shared bymultiple UEs for ePDCCHs in a common search space. In such examples, itcan be beneficial to broadcast the common PUCCH resource offsets in amessage on a common control channel, or to specify predetermined valuesof the common PUCCH resource offsets such that the values are known toboth the network and UE (e.g. by including the values of the commonPUCCH resource offset in future physical layer specifications). ThePUCCH resource offsets corresponding to UE specific search spaces and/orlocalized ePDCCH may be specific to each UE, and so may be signaled toeach UE independently using dedicated messaging, e.g. via RRC signaling.

An example operation 1200 of this first disclosed example of extendedimplicit PUCCH resource allocation when G>1 is illustrated in FIG. 12for two example UEs 6 and 7. When G=1, given their particular ePDCCHpositions, aggregation levels, and MIMO layers, UEs 6 and 7 of FIG. 12will map to the same PUCCH resources unless N_(ePUCCH)⁽¹⁾(6,n_(type))≠N_(ePUCCH) ⁽¹⁾(7,n_(type)). However, if G>1, it ispossible to have N_(ePUCCH) ⁽¹⁾(6,n_(type))=N_(ePUCCH) ⁽¹⁾(7,n_(type)).In one example approach, G is selected to be a fraction of the totalPUCCH resource available in a subframe. In general, └k/L┘ tends to beless than N′_(ePUCCH) because the average value of L is greater thanone. Therefore large valued PUCCH resources are not as likely to beallocated when m=0 and N_(ePUCCH) ⁽¹⁾(u,n_(type))=0. When the maximumvalue of └k/L┘ is approximately N′_(ePUCCH)/2, G can be chosen to be,for example, G=N′_(ePUCCH)/2. Applying Equation 8 and takingN′_(PUCCH)=16 for example, the PUCCH resources for UEs 6 and 7 of FIG.12 are then n_(PUCCH,UE7) ⁽¹⁾=mod(└4/2┘+8·1,16)+N_(ePUCCH)⁽¹⁾(6,n_(type))=10+N_(ePUCCH) ⁽¹⁾(6,n_(type)) and n_(PUCCH,UE7)⁽¹⁾=mod(└2/2┘+8·2,16)+N_(ePUCCH) ⁽¹⁾(7,n_(type))=1+N_(ePUCCH)⁽¹⁾(7,n_(type)). In such an example, even if N_(ePUCCH)⁽¹⁾(6,n_(type))=N_(ePUCCH) ⁽¹⁾(7,n_(type)), different PUCCH resourceswill be allocated to UEs 6 and 7.

The benefit of using the mod( ) operator of this first disclosed examplecan also be seen considering UE 7 of FIG. 12 when G>1. If the mod( )operator is omitted, Equation 8 becomes n_(PUCCH)⁽¹⁾=└k/L┘+Gm+N_(ePUCCH) ⁽¹⁾(u,n_(type)), and the resource allocated toUE 7 would therefore be n_(PUCCH,UE7) ⁽¹⁾=└2/2┘+8·2+N_(ePUCCH)⁽¹⁾(7,n_(type))=17+N_(ePUCCH) ⁽¹⁾(7,n_(type)). When N_(ePUCCH)⁽¹⁾(7,n_(type))≧0, then n_(PUCCH,UE7) ⁽¹⁾=17+N_(ePUCCH)⁽¹⁾(7,n_(type))>N′_(ePUCCH), and UE 7 could be allocated a PUCCHresource that is greater than the number available. Therefore, a benefitof the mod( ) operator is to ensure that valid PUCCH resourceallocations are used even when └k/L┘+Gm is large, as might happen whenan ePDCCH is transmitted on an antenna port or an MU-MIMO layer with ahigh index.

It may be possible to restrict the ePDCCH allocations such that └k/L┘+Gmis not large. Therefore, in an alternate disclosed example of extendedimplicit resource allocation, PUCCH resources are allocated usingEquation 9 below.

n _(PUCCH) ⁽¹⁾ =└k/L┘+Gm+N _(ePUCCH) ⁽¹⁾(u,n _(type)).   Equation 9

The simplifications used for the example of Equation 8 can also apply tothe disclosed example of Equation 9. For example, if m is not needed(such as when MU-MIMO is not used on ePDCCH), it can be omitted, orequivalently set to m=0. Also, G can be omitted (equivalently set G=1)if not needed.

It may be desirable to identify ePDCCH transmissions using the DMRS portthey are transmitted on instead of the more general DMRS configurationindex defined in the disclosed example of Equation 5. Therefore, inanother alternate disclosed example of extended implicit resourceallocation, m in Equation 8 and/or Equation 9 can be associated with aDMRS port instead of an antenna port. For example, m=p−7, where p ∈{7,8,9,10} is a DMRS port that at least a portion of the ePDCCH istransmitted to the UE on.

Since a PUCCH ACK/NACK transmission can be in response to a PDSCHtransmission, it may be beneficial to use PDSCH parameters rather thanto use parameters of an ePDCCH scheduling the PDSCH transmission. Forexample, such an approach may be appropriate for subframes where allPDSCHs are scheduled by ePDCCH and there is no PDCCH on a carrier.Subframes of the so called ‘New Carrier Type’ (NCT) discussed for LTERel-11 standards could have such configuration. Therefore, in anotheralternate disclosed example of extended implicit resource allocation, kin Equation 8 and/or Equation 9 is associated with PDSCH resourcesinstead of ePDCCH location. For example, k=n_(PDSCH), where n_(PDSCH) isthe location of the PDSCH in PDSCH resources, which may be an index ofone of the PDSCH PRBs (such as the first PRB) of the PDSCH transmission.

When an LTE UE is configured to transmit PUCCH format 1b with channelselection, or when it is configured to transmit PUCCH using transmitdiversity, the UE may be allocated multiple PUCCH resources. In such, ina second disclosed example type of extended implicit resource allocation(e.g., targeted for channel selection or transmit diversity), at least asecond PUCCH resource, in addition to a first PUCCH resource, isallocated to a UE. The mapping function for this example type ofextended implicit resource allocation is given by below:

n _(PUCCH,i) ^((1,p=p) ^(j) ^()=mod() F└k/L┘+Gm+Hδ _(i,j) +N _(Δ) ,N′_(ePUCCH))+N _(ePUCCH) ⁽¹⁾(u,n _(type))   Equation 10

In Equation 10, the variables as defined for Equation 8 are the same,and Equation 10 also includes the following parameters:

n_(PUCCH,i) ^((1,p=p) ^(j) ⁾ is the i^(th) PUCCH resource the UE maytransmit on. It may be represented by a vector of one or more PUCCHresources the UE may transmit on, n_(PUCCH) ⁽¹⁾. If transmit diversityis configured, elements can include n_(PUCCH,i) ^((1,p=p) ⁰ ⁾ which istransmitted on the first antenna port p₀, and n_(PUCCH,i) ^((1,p=p) ¹ ⁾which is transmitted on the second antenna port p₁. If transmitdiversity is not configured, then n_(PUCCH) ⁽¹⁾ may contain only oneelement n_(PUCCH,i) ^((1,p=p) ⁰ ⁾.

F is an integer used to allow ePDCCHs with adjacent values of └k/L┘ tobe mapped to non-adjacent PUCCH resources. It can be omitted(equivalently set F=1) if not needed;

i is a non-negative integer index of the allocated PUCCH resources onantenna port p₀ and on antenna port p₁. If two PUCCH resources areallocated to an antenna port, then i=0 or i=1;

j is a non-negative integer index of the antenna port PUCCH resource maybe transmitted upon;

δ_(i,j) is a non-negative integer indicating secondary PUCCH resourceoffset. It may be used to allocate more PUCCH resources to a UE. Forexample, it may be used when PUCCH transmit diversity is configured, orfor format 1b with channel selection when a UE may receive a PDSCHcontaining two transport blocks;

H is an integer used to allow ePDCCHs with different PUCCH resourceoffset δ_(i,j) to be mapped farther apart in PUCCH resources. It can beomitted (equivalently set H=1) if not needed;

N_(Δ) is a time varying integer PUCCH resource offset determined in eachsubframe that may be used when PDSCHs from more than one downlinksubframe require Ack/Nack in TDD systems. If N_(Δ) is not needed, it canbe omitted, or equivalently set to 0;

In the following descriptions of extended implicit resource allocation,N_(Δ)=0 unless indicated otherwise, in order to simplify thediscussions. It should be understood that non-zero values can be used inthese disclosed examples when non-zero values of N_(Δ) are needed.

In a disclosed example of the second type of extended implicit resourceallocation, when (1) PUCCH format 1b with channel selection is used, (2)transmit diversity is not configured for the UE and (3) the UE isconfigured for a downlink transmission mode that supports up to twotransport blocks and is granted a PDSCH transmission indicated by acorresponding ePDCCH, then n_(PUCCH) ⁽¹⁾ contains two PUCCH resourcesfor antenna port p₀, namely, n_(PUCCH,0) ^((1,p=p) ⁰ ⁾ and n_(PUCCH,1)^((1,p=p) ⁰ ⁾. The two corresponding secondary PUCCH resource offsetsare δ_(0,0)=0 and δ_(1,0)=1. In such an example, n_(PUCCH,0) ^((1,p=p) ⁰⁾=mod(F└k/L┘+Gm,N′_(ePUCCH))+N_(ePUCCH) ⁽¹⁾(u,n_(type)) and n_(PUCCH,1)^((1,p=p) ⁰ ⁾=mod(F└k/L┘+1·H,N′_(ePUCCH))+N_(ePUCCH) ⁽¹⁾(u,n_(type)).When └k/L┘+Gm+1<N′_(ePUCCH) and both F=1 and H=1 (or they are not used),then n_(PUCCH,1) ^((1,p=p) ⁰ ⁾=n_(PUCCH,0) ^((1,p=p) ⁰ ⁾+1, which isconsistent with how resource allocation channels selection for MIMO isspecified in LTE Rel-10.

When F=1 and H=1 in this disclosed example of the second type ofextended implicit resource allocation, ePDCCHs with adjacent values of└k/L┘ can have PUCCH resource allocations that conflict when MIMO orPUCCH transmit diversity (T×D) is configured. An example operation 1300of this second type of extended implicit resource allocation isillustrated in FIG. 13. When MIMO is configured, but PUCCH T×D is not,and taking N′_(ePUCCH)=16 and G=N′_(ePUCCH)/2, then UE8 of FIG. 13 willbe allocated PUCCH resources n_(PUCCH,UE8,0) ^((1,p=p) ⁰⁾=mod(1·└2/2┘+8·1+1·0,16)+N_(ePUCCH) ⁽¹⁾(8,n_(type))=9+N_(ePUCCH)⁽¹⁾(8,n_(type)) and n_(PUCCH,UE8,0) ^((1,p=p) ¹⁾=mod(1·└2/2┘+8·1+1·1,16)+N_(ePUCCH) ⁽¹⁾(8,n_(type))=10+N_(ePUCCH)⁽¹⁾(8,n_(type)). Similarly, UE9 of FIG. 13 will be allocated PUCCHresources n_(PUCCH,UE9,0) ^((1,p=p) ⁰⁾=mod(1·└4/2┘+8·1+1·0,16)+N_(ePUCCH) ⁽¹⁾(9,n_(type))=10+N_(ePUCCH)⁽¹⁾(9,n_(type)) and n_(PUCCH,UE9,0) ^((1,p=p) ¹⁾=mod(1·└4/2┘+8·1+1·1,16)+N_(ePUCCH) ⁽¹⁾(9,n_(type))=11+N_(ePUCCH)⁽¹⁾(9,n_(type)). In the illustrated example, n_(PUCCH,UE8,0) ^((1,p=p) ¹⁾=n_(PUCCH,UE9,0) ^((1,p=p) ⁰ ⁾, so the PUCCH resource allocation for UE8 on antenna port 1 is the same as the one for UE 9 on antenna port 0when N_(ePUCCH) ⁽¹⁾(8,n_(type))=N_(ePUCCH) ⁽¹⁾(9,n_(type)).

PUCCH resource conflicts in the situation just described can be avoidedby setting F>1. UEs requiring the same number of PUCCH resources can begrouped together, and the value of F can be set to the number ofresources needed per UE. For example, two PUCCH resources may be neededper UE when MIMO is configured, but PUCCH T×D is not. In such example,we can set F=2. In such examples, UE8 of FIG. 13 will be allocated PUCCHresources n_(PUCCH,UE8,0) ^((1,p=p) ⁰⁾=mod(2·└2/2┘+8·1+1·0,16)+N_(ePUCCH) ⁽¹⁾(8,n_(type))=10+N_(ePUCCH)⁽¹⁾(8,n_(type)) and n_(PUCCH,UE8,0) ^((1,p=p) ¹⁾=mod(2·└2/2┘+8·1+1·1,16)+N_(ePUCCH) ⁽¹⁾(8,n_(type))=11+N_(ePUCCH)⁽¹⁾(8,n_(type)). Similarly, UE9 of FIG. 13 will be allocated PUCCHresources n_(PUCCH,UE9,0) ^((1,p=p) ⁰⁾=mod(2·└4/2┘+8·1+1·0,16)+N_(ePUCCH) ⁽¹⁾(9,n_(type))=12+N_(ePUCCH)⁽¹⁾(9,n_(type)) and n_(PUCCH,UE9,0) ^((1,p=p) ¹⁾=mod(2·└4/2┘+8·1+1·1,16)+N_(ePUCCH) ⁽¹⁾(9,n_(type))=13+N_(ePUCCH)⁽¹⁾(9,n_(type)). Therefore even when N_(ePUCCH)⁽¹⁾(8,n_(type))=N_(ePUCCH) ⁽¹⁾(9,n_(type)), all 4 PUCCH resources aredistinct, and there is no conflict.

The PUCCH resource conflicts described above can also be avoided bysetting H>1. In such examples, H can be set in a manner similar to G,where H is selected to be a significant fraction of the total PUCCHresource available in a subframe. When the maximum value of F└k/L┘ isapproximately N′_(ePUCCH)/2, we can choose H=N′_(ePUCCH)/2. Forsimplicity, it may be desirable in some disclosed examples to set F=1when H>1. It may also be desirable for further simplicity toadditionally set H=G.

The operation of this disclosed example when H >1 and F=N′_(ePUCCH)/2may be understood considering UEs 8 and 9 of FIG. 13. For example, twoPUCCH resources may be needed per UE when MIMO is configured, but PUCCHT×D is not. In such examples, we can set F=2. In such examples, UE8 ofFIG. 13 will be allocated PUCCH resources n_(PUCCH,UE8,0) ^((1,p=p) ⁰⁾=mod(1·└2/2┘+8·1+8·0,16)+N_(ePUCCH) ⁽¹⁾(8,n_(type))=8+N_(ePUCCH)⁽¹⁾(8,n_(type)) and n_(PUCCH,UE8,0) ^((1,p=p) ¹⁾=mod(1·└2/2┘+8·1+8·1,16)+N_(ePUCCH) ⁽¹⁾(8,n_(type))=0+N_(ePUCCH)⁽¹⁾(8,n_(type)). Similarly, UE9 of FIG. 13 will be allocated PUCCHresources n_(PUCCH,UE9,0) ^((1,p=p) ⁰⁾=mod(1·└4/2┘+8·1+8·0,16)+N_(ePUCCH) ⁽¹⁾(9,n_(type))=10+N_(ePUCCH)⁽¹⁾(9,n_(type)) and n_(PUCCH,UE9,0) ^((1,p=p) ¹⁾=mod(1·└4/2┘+8·1+8·1,16)+N_(ePUCCH) ⁽¹⁾(9,n_(type))=2+N_(ePUCCH)⁽¹⁾(9,n_(type)). Therefore even when N_(ePUCCH)⁽¹⁾(8,n_(type))=N_(ePUCCH) ⁽¹⁾(9,n_(type)), all 4 PUCCH resources aredistinct, and there is no conflict.

When a UE (e.g., the UE 105) is configured for PUCCH transmit diversityand for a downlink transmission mode that supports up to one transportblock, the same PUCCH resource allocation method can be used withdifferent antenna ports, such that n_(PUCCH) ⁽¹⁾ contains two PUCCHresources, namely, n_(PUCCH,0) ^((1,p=p) ⁰ ⁾ and n_(PUCCH,0) ^((1,p=p) ¹⁾. Here, the two corresponding PUCCH secondary resource offsets areδ_(0,0)=0 and δ_(1,0)=1. Therefore, n_(PUCCH,0) ^((1,p=p) ⁰⁾=mod(F└k/L┘+Gm+H·0, N′_(ePUCCH))+N_(ePUCCH) ⁽¹⁾(u,n_(type)) and when└k/L┘+Gm+1<N′_(ePUCCH) and both F=1 and H=1 (or they are not used),n_(PUCCH,0) ^((1,p=p) ¹ ⁾=n_(PUCCH,0) ^((1,p=p) ⁰ ⁾+1, which isconsistent with how PUCCH transmit diversity is specified in LTE Rel-10.

More PUCCH resources may be needed when a UE is configured for PUCCHtransmit diversity and for a downlink transmission mode that supports upto two transport blocks. In such examples, 4 PUCCH resources may beneeded, with the 4 corresponding PUCCH secondary resource offsets being:δ_(0,0)=0, δ_(0,1)=2. δ_(1,0)=1 and δ_(1,1)=3. PUCCH resources ate thenallocated as: n_(PUCCH,0) ^((1,p=p) ⁰⁾=mod(F└k/L┘+Gm+H·0,N′_(ePUCCH))+N_(ePUCCH) ⁽¹⁾(u,n_(type)), n_(PUCCH,0)^((1,p=p) ¹ ⁾=mod(F└k/L┘+Gm+H·2,N′_(ePUCCH))+N_(ePUCCH) ⁽¹⁾(u,n_(type)),n_(PUCCH,1) ^((1,p=p) ⁰ ⁾=mod(F└k/L┘+Gm+H·1,N′_(ePUCCH))+N_(ePUCCH)⁽¹⁾(u,n_(type)), and n_(PUCCH,1) ^((1,p=p) ¹⁾=mod(F└k/L┘+Gm+H·3,N′_(ePUCCH))+N_(ePUCCH) ⁽¹⁾(u,n_(type)). Note thatwhen └k/L┘+Gm+3<N′_(ePUCCH) and both F=1 and H=1 (or they are not used),n_(PUCCH,1) ^((1,p=p) ⁰ ⁾=n_(PUCCH,0) ^((1,p=p) ⁰ ⁾+1, n_(PUCCH,0)^((1,p=p) ¹ ⁾=n_(PUCCH,0) ^((1,p=p) ⁰ ⁾+2, and n_(PUCCH,1) ^((1,p=p) ¹⁾=PUCCH,1 ^((1,p=p) ⁰ ⁾+2.

In a TDD system, a UE may receive an ePDCCH in each of multiple DLsubframes and transmit all the corresponding A/N bits in one ULsubframe. In such examples, it may be allocated multiple PUCCH resourcescorresponding to the PDSCHs in the different subframes. In suchexamples, it can be desirable for the amount of required PUCCH resourceto grow with both the number of PUCCH resources allocated to a UE in asubframe, as well as the size of the ePDCCH region. In that way, theamount of PUCCH resources can be reduced when a UE is scheduled fewerPDSCHs and when fewer UEs are scheduled in a subframe. One exampleapproach to achieve this, which is compatible with LTE Rel-10 TDD PUCCHresource allocation, is to allocate higher PUCCH resource indices forUEs scheduled with higher ePDCCH indices (that is, those with highervalues of └k/L┘), and for the PDSCHs with higher time indices, asfurther described below. Therefore, a first example allocationtechniques uses a time varying PUCCH resource offset, N_(Δ), which maybe calculated using the following equation:

N _(Δ)=(O−o−1)·N _(c) +o·N _(c+1).   Equation 11

In Equation 11 the UE first selects a c value out of {0, 1, 2, . . . ,C_(ePDCCH) ^(max)−1} which makesN_(c)≦mod(F└k/L┘+Gm+Hδ_(i,j),N′_(ePUCCH))≦N_(c+1), and the parameters ofEquation 11 are:

O is a number of DL subframes with PDSCH transmissions requiring anAck/Nack response in an uplink subframe;

o is a non-negative integer time index corresponding to one of the O DLsubframes, and has a range of 0≦o<O;

N _(c)=max{0,└[N _(RB) ^(DL)·(N _(sc) ^(RB) ·c−D ₀)]/D ₁┘};

C_(PDCCH) ^(max) is the number of distinct sizes that an ePDCCH regioncan be set to;

D₀ is an integer representing the expected subcarriers averaged over allvalues of c that cannot be used for ePDCCH data in a PRB, such assubcarriers reserved for reference signals. An example value may beD₀=4;

D₁ is a real valued scale factor to adjust the number of allocated PUCCHresources to more closely match to the number of needed PUCCH resources.One example value may be D₁=36·D₂, where D₂ is may be set to a valuegreater than 1;

N_(RB) ^(DL) is the number of downlink resource blocks on a carrier in asubframe, as defined in, for example, 3GPP TS 36.211 V10.1.0 (Mar. 20,2011), which is hereby incorporated by reference in its entirety; and

N_(sc) ^(RB) is the resource block size in the frequency domain,expressed as a number of subcarriers as defined in, for example, 3GPP TS36.211 V10.1.0.

Alternatively, N_(c) may be calculated according to the maximum amountof PUCCH resource associated with ePDCCH and how many different sizes anePDCCH region can have. For example, the following equation may be used:

N _(c) =└cN _(ePUCCH) ^(max) /C _(ePDCCH) ^(max)┘  Equation 12

In Equation 12, N_(ePUCCH) ^(max) is the maximum total number of PUCCHresources available for ePDCCH in any subframe.

Because the formula for N_(Δ) and N_(c) may not change, they may befixed in future physical layer specifications.

As another example, N_(Δ) can be determined using higher layersignaling. For example, a list of C_(ePDCCH) ^(max) values for N_(c) canbe indicated to the UE using RRC signaling or on a system informationblock transmitted using PBCH. An element of the list of values for N_(c)with index c is selected from the list, where c is determined as above.The selected value is then used to determine N_(Δ) using Equation 11above.

A third example UE process 1400 that may be executed to implement theexample UE UCC resource allocator 125 of FIG. 1 is illustrated in FIG.14. A corresponding third example eNB process 1500 that may be executedto implement the example eNB UCC resource allocator 130 of FIG. 1 isillustrated in FIG. 15. The third example processes 1400 and 1500implement a third example solution (also referred to herein as examplesolution #3) disclosed herein for performing PUCCH resource allocationfor an ePDCCH. Example solution #3 corresponds to resource allocationinvolving dynamic signaling of an ack/nack (A/N) PUCCH resource regionto a UE (e.g., the UE 105). For example, multiple A/N PUCCH resourceregions may be semi-statically configured for a UE. Then, a particularA/N PUCCH resource region may be selected dynamically through DCI foreach PDSCH scheduled by an ePDCCH. Within the selected region, anyappropriate technique, such as a mapping table, a hash function, etc.,such as those defined in example solutions #1 or 2 discussed above,could be used to map between an ePDCCH scheduled PDSCH and an A/N PUCCHresource. Additionally or alternatively, a hash function based on a UEidentifier could be used to determine the allocated PUCCH resource inthe signaled A/N PUCCH resource region.

With the foregoing in mind, and with reference to the preceding figuresand associated descriptions, the example process 1400 of FIG. 14 beginsexecution at block 1405 at which the UE UCC resource allocator 125 ofthe UE 105 obtains (e.g., via signaling from the eNB 110 and/or anyother manner) any uplink control channel allocation parameters to beused for performing PUCCH resource allocation. Additionally, at block1405, the UE UCC resource allocator 125 obtains (e.g., via signalingfrom the eNB 110 and/or any other manner) information related tospecification of multiple A/N PUCCH resource regions. At block 1410, theUE UCC resource allocator 125 obtains (e.g., via signaling from the eNB110 and/or any other manner) an indication specifying a particular A/NPUCCH resource region allocated to the UE 105 from among the multipleA/N PUCCH resource regions configured at block 1405. For example, theindication may be carried in a control channel transmitted from the eNB110 to the UE 105 (e.g. such as in DCI carried in an ePDCCH).

At block 1415, the UE UCC resource allocator 125 uses any appropriatetechnique (such as, but not limited to, a technique based on solutions#1 and/or #2 described above) to select an allocated PUCCH resource fromthe particular A/N PUCCH resource region allocated to the UE 105 atblock 1410. In some examples, the UE UCC resource allocator 125 may useinformation determined from receiving an ePDCCH carrying the indicationspecifying the particular A/N region to select the allocated PUCCH A/Nresource. For example, the UE 105 may determine the position (e.g. aneCCE index) of the ePDCCH, and the UE UCC resource allocator 125 may mapthe position to a resource in the particular PUCCH A/N region (e.g.,according to Equation 13 discussed in detail below). Then, at block1420, the UE 105 transmits on the allocated PUCCH resource.

Correspondingly, the example process 1500 of FIG. 15 begins execution atblock 1505 at which the eNB UCC resource allocator 130 of the eNB 110provides (e.g., via signaling and/or any other appropriate manner) tothe UE 105 any uplink control channel allocation parameters to be usedfor performing PUCCH resource allocation, including the informationrelated to specification of the multiple A/N PUCCH resource regions. Atblock 1510, the eNB UCC resource allocator 130 provides (e.g., viasignaling and/or any other manner) the indication specifying aparticular A/N PUCCH resource region allocated to the UE 105 from amongthe multiple A/N PUCCH resource regions configured at block 1505. Forexample, the indication may be carried in a control channel transmittedfrom the eNB 110 to the UE 105 (e.g. such as in DCI carried in anePDCCH). In some examples, the ePDCCH carrying the indication may alsobe used to select an allocated PUCCH A/N resource by determining theposition (e.g. an eCCE index) of the ePDCCH and mapping it to a resourcein the particular PUCCH A/N region (e.g., according to Equation 13discussed in detail below). At block 1515, the eNB 110 determines theposition (e.g. an eCCE index) at which it will transmit the ePDCCH. TheeNB 110 then transmits the ePDCCH to the UE 105 at the determinedposition.

An example operation 1600 of the example processes 1400 and 1500implementing example solution #3 is illustrated in FIG. 16. In theillustrated example operation 1600 of FIG. 16, PUCCH resources forePDCCH are reserved separately from those of PDCCH, the latter of whichis labeled as region ‘A’. In some examples, region ‘A’ can overlap withother regions. In the illustrated example of FIG. 16, ePDCCH relatedPUCCH resources are broken into 4 regions (labeled and ‘B’, ‘C’, ‘D’, ‘Ein the figure), each of which may be addressed by two (2) bits in DCImessages carried on ePDCCH. In the example operation 1600, the locationwithin a region, e.g., region ‘B’, for UE 105 is first determined by theeNB UCC resource allocator 130 of the eNB 110. If the determinedlocation conflicts with an allocation for another UE, a location for theUE is calculated in another region, e.g., region ‘C’, by the eNB UCCresource allocator 130. If the determined location still conflicts,subsequent regions are tested by the eNB UCC resource allocator 130until a region that does not conflict is found or until there are nomore regions. The region without conflict is selected, and sent as a 2bit address in the DCI message to the UE 105 by the eNB 110.

Further details concerning example solution #3, which corresponds toPUCCH resource allocation based on dynamic PUCCH resource regionindication signaled in DCI and which may be implemented by the exampleprocesses 1400 and/or 1500, are now provided. Per the discussion above,multiple A/N PUCCH resource regions could be semi-statically configuredfor ePDCCH scheduled PDSCH. A UE (e.g., the UE 105) can be dynamicallyindicated in a DCI carried by an ePDCCH about which PUCCH resourceregion a corresponding A/N PUCCH resource is allocated. As mentionabove, an example 1600 of solution #3 is shown in FIG. 16. In theexample operation 1600, four PUCCH resource regions, namely {B,C,D,E},are defined for ePDCCH scheduled PDSCH and one of the four regions isdynamically indicated by two bits in the DCI carried by the ePDCCH.

The PUCCH resource regions may have the same or different sizes. Thefour regions shown in FIG. 16 may overlap, and may overlap with regionA, which is where the PUCCH A/N resources corresponding to the legacyPDCCH are allocated in the illustrated example. For example, each PUCCHresource region can be defined by a starting PUCCH resource index and/ora size. In some examples, configuration information for the regions canbe semi-statically signaled to a UE through higher layers (e.g., via RRCsignaling). In other examples, the regions can be predefined.

Within each of the PUCCH resource regions, a mapping function or a hashfunction, such as that given by Equation 5 or Equation 8, can be used todetermine the A/N PUCCH resource to be allocated to the UE. In suchexamples, each PUCCH resource region is then defined by either the ARI() in Equation 5, or N′_(PUCCH) and N_(ePUCCH) ⁽¹⁾(u,n_(type)) inEquation 8.

In some examples, the ePDCCH resources may be mapped to PUCCHresource(s) within a resource region by compressing the position indicesto map to within a resource region. For example, such a compressionmapping can be accomplished by setting the PUCCH resource using a sum ofoffsets calculated at a UE (e.g., the UE 105) and an eNB (e.g., the eNB110), respectively, according to Equation 13:

n _(PUCCH,i) ^((1,p=p) ^(j) ⁾ =└k/L┘+Gm+Hδ _(i,j) +rN _(ePUCCH,r) +N_(ePUCCH) ⁽¹⁾(u,n _(type))   Equation 13

Equation 13 includes the following parameters:

n_(PUCCH,i) ^((1,p=p) ^(j) ⁾ is the PUCCH resource the UE may transmiton antenna port p_(j), as described in Equation 10;

k is an integer that identifies the location of an ePDCCH containing adownlink grant to the UE, or that identifies the location of a PDSCHtransmission containing data for the UE;

N_(r) is the number of PUCCH regions;

m is a non-negative time index. For TDD, it corresponds to the subframein which the PDSCH was transmitted that n_(PUCCH,i) ^((1,p=p) ^(j) ⁾corresponds to. For FDD, m is fixed at m=0;

N_(ePUCCH,r) is the number of PUCCH resources in region r;

r ∈ {0,1, . . . , N_(r)-1} is the assigned PUCCH region;

G is an integer used to allow PUCCH resources for subframes withdifferent time indices to be mapped farther apart within a PUCCH region.One desirable value may be G=└N_(eCCE)/N_(r)┘, where N_(eCCE) is anumber of eCCEs in a subframe. This parameter can be omitted(equivalently set G=1) if not needed;

H is an integer used to allow ePDCCHs with different PUCCH resourceoffset δ_(i,j) to be mapped farther apart in PUCCH resources. Thisparameter can be omitted (equivalently set H=1) if not needed;

N_(ePUCCH) ⁽¹⁾(u,n_(type)), u, δ_(i,j), and n_(type) may be defined andused as in extended implicit resource allocation, including as inEquation 8 and Equation 10.

By using Equation 13, the PUCCH region is set by r·N_(ePUCCH,r) and thelocation within the PUCCH region is set by └k/N_(r)┘+Gm+Hδ_(i,j). Basedon typical parameter values expected to be used in at least some exampleLTE systems, a majority of the magnitudes of the offset └k/N_(r)┘ isexpected to be smaller than a maximum magnitude of the offsetrN_(ePUCCH,r) in Equation 13.

In another example, in each PUCCH resource region, a new hash functioncan be used, which based on a UE ID (e.g., such as the cell RNTI orC-RNTI) and the subframe index over which the ePDCCH is received. Thepurpose of the hash function is to generate a pseudo random output for agiven UE ID and a subframe index. An example of such a hash function isgiven by Equation 14:

n _(PUCCH,i) ⁽¹⁾(n _(RNTI) ,k)=mod(Y _(k) ,M _(PUCCH) ^(i))+N _(PUCCH)^(i)   Equation 14

Equation 14 includes the following parameters:

n_(PUCCH,i) ⁽¹⁾(n_(RNTI),k) is the PUCCH resource in the i^(th) PUCCHregion for a UE with C-RNTI , n_(RNTI), and ePDCCH scheduled PDSCH insubframe k;

N^(i) _(PUCCH) ^(i) and M_(PUCCH) ^(i) are, respectively, the startingPUCCH index and the size of the i^(th) PUCCH region;

Y_(k) is a pseudo random number and an example is given by Equation 15:

Y _(k)=mod(P·Y _(k−1) ,Q)   Equation 15

For example, the parameters of Equation 15 can be set to P=39827,Q=65537, and Y⁻¹=n_(RNTI)≠0.

Example solution #3 employing the hash function of Equation 14 can beused for both FDD and TDD systems. For TDD systems, A/N information forPDSCHs scheduled in multiple DL subframes may be transmitted in one ULsubframe. Because of the subframe dependent pseudo number generationdescribed above, different PUCCH resources can be derived for PDSCHsscheduled to the same UE but in multiple DL subframes. If the eNB (e.g.,the eNB 110) can perform multi-frame scheduling (e.g., in which the eNBmakes scheduling decisions for both the current DL subframe as well asfuture DL subframes before the next UL subframe), then the PUCCHresources for the same UE can be allocated in the same PUCCH region. Insuch examples, only the first PUCCH resource is obtained for a UE byperforming the hash function based on the UE ID and one of the DLsubframe numbers, e.g. the first DL subframe. The rest of the PUCCHresources for the UE can be continuously allocated after the first PUCCHresource.

When two transport blocks (TBs) are scheduled for a PDSCH on the primarycarrier and PUCCH format 1b with channel selection is configured, thenthe PUCCH resources are given by {n_(PUCCH,i) ⁽¹⁾(n_(RNTI),k),n_(PUCCH,i) ⁽¹⁾(n_(RNTI),k)+1}.

In case of cross carrier scheduling, a UE can be scheduled through aprimary carrier with two PDSCHs each transmitted on a different carrier.In such examples, a UE (e.g., the UE 105) could receive two ePDCCHs onthe primary carrier. A/N PUCCH resources for each of the PDSCHs are thenallocated. One way to perform such PUCCH resource allocation usingsolution #3 is to map the PUCCH resources continuously starting fromn_(PUCCH,i) ⁽¹⁾(n_(RNTI),k). For example, assuming that the PDSCH on theprimary carrier has two TBs and the PDSCH on the secondary carrier hasone TB, then with PUCCH format 1b with channel selection and one antennais used for PUCCH transmission, the PUCCH resources are given by{n_(PUCCH,i) ⁽¹⁾(n_(RNTI),k), n_(PUCCH,i) ⁽¹⁾(n_(RNTI),k)+1, n_(PUCCH,i)⁽¹⁾(n_(RNTI),k)+2}.

If two antennas are used for the A/N PUCCH transmission, then the PUCCHresources on the second antenna can be given by {n_(PUCCH,i)⁽¹⁾(n_(RNTI),k)+3, n_(PUCCH,i) ⁽¹⁾(n_(RNTI),k)+1, n_(PUCCH,i)⁽¹⁾(n_(RNTI),k)+2}.

With this dynamic PUCCH region selection, the A/N PUCCH resources can beadjusted in a subframe by subframe basis depending on the number ofPDSCHs scheduled. When the number of PDSCHs scheduled by ePDCCH is smallin a subframe and a subset of the A/N PUCCH resources is enough tosupport all the A/N feedback, all the UEs may be allocated to a singleA/N PUCCH region and the rest of the regions can be used for physicaluplink shared channel (PUSCH) transmission. When the number of PDSCHsscheduled in a subframe is large, different UEs may be distributed todifferent A/N PUCCH regions in order to accommodate the large number ofA/N feedbacks. The overall size of the A/N PUCCH regions can be designedto accommodate the largest number of possible PDSCHs scheduled in asubframe by ePDCCH. The number of regions can be designed by consideringboth the dynamic signaling overhead and the reduction of A/N resourceoverhead. For example, two bits can be used to support four regions,while one bit can be used to support two regions.

In some examples, the A/N PUCCH resource regions can be semi-staticallysignaled. The size of the regions can be either the same or different.The regions may be contiguous or non-contiguous.

A possible benefit of example solution #3 is that the A/N resourceoverhead can be reduced dynamically by adjusting the number of A/N PUCCHresource regions used based on the number of PDSCHs scheduled in asubframe. The cost is the signaling overhead, as some additional bitsare needed in the DCI to signal the A/N PUCCH resource regioninformation.

A fourth example UE process 1700 that may be executed to implement theexample UE UCC resource allocator 125 of FIG. 1 is illustrated in FIG.17. A corresponding fourth example eNB process 1800 that may be executedto implement the example eNB UCC resource allocator 130 of FIG. 1 isillustrated in FIG. 18. The fourth example processes 1700 and 1800implement a fourth example solution (also referred to herein as examplesolution #4) disclosed herein for performing PUCCH resource allocationfor an ePDCCH. Example solution #4 corresponds to PUCCH resourceallocation with PUCCH resource remapping.

In PUCCH resource remapping, CCEs are organized into groups according ton _(CCE)≡mod(n_(CCE),L₀), such that a set of CCEs that have n _(CCE)=iis referred to as CCE group i, and L₀ as the number of CCE groups. Insome examples, L₀ is chosen to be a multiple of, or equal to, theaggregation levels of the available ePDCCHs. In PUCCH resourceremapping, CCEs within a CCE group are mapped to one or more regions ofadjacent PUCCH resources, and CCE groups with the highest probability ofoccurrence are mapped to lower PUCCH resources.

Example solution #4 can be further customized for TDD. For example, thevalue of N_(c) (which is discussed in greater detail below) can beadjusted to concentrate CCE group occupancy more than can be achieved inLTE Rel-10. In some examples, solution #4 also uses a block-basedremapping to support cases where there are multiple downlink subframesrequiring Ack/Nack in one uplink subframe.

With the foregoing in mind, and with reference to the preceding figuresand associated descriptions, the example process 1700 of FIG. 17 beginsexecution at block 1705 at which the UE UCC resource allocator 125 ofthe UE 105 obtains (e.g., via signaling from the eNB 110 and/or anyother manner) any uplink control channel allocation parameters to beused for performing PUCCH resource allocation. The uplink controlchannel allocation parameters may include parameters for use inevaluating a permutation function (described in greater detail below) tobe used to remap CCE groups. In some examples, the permutation functionmay be known at the UE 105 (e.g., via specification in an appropriatecommunication standard), whereas in other examples, the permutation maybe provided to the UE 105 (e.g., via signaling from the eNB 110). Atblock 1715, the UE UCC resource allocator 125 determines a DMRSidentifier based on DMRS information associated with an ePDCCHtransmission to be received by the UE 105. At block 1720, the UE 105receives an ePDCCH transmission for which one or more PUCCH resourcesare to be allocated. At block 1725, the UE UCC resource allocator 125determines a position (e.g., an eCCE index) of the received ePDCCHtransmission.

As described in greater detail below, at block 1730, the UE UCC resourceallocator 125 processes the determined position of the received ePDCCHtransmission to determine a scaled index and a first CCE group index. Atblock 1735, the UE UCC resource allocator 125 processes the first CCEgroup index with the permutation function to determine a second CCEgroup index. At block 1740, the UE UCC resource allocator 125 processesthe scaled index, the second CCE group index and the DMRS identifierwith a mapping function, as described in greater detail below, todetermine an allocated PUCCH resource. At block 1745, the UE 105transmits on the allocated PUCCH resource.

Correspondingly, the example process 1800 of FIG. 18 begins execution atblock 1805 at which the eNB UCC resource allocator 130 of the eNB 110provides (e.g., via signaling and/or any other appropriate manner) tothe UE 105 any uplink control channel allocation parameters to be usedfor performing PUCCH resource allocation. The uplink control channelallocation parameters may include parameters for use by the UE 105 whenevaluating the permutation function to be used to remap CCE groups whenperforming PUCCH resource allocation with PUCCH resource remapping. Atblock 1810, the eNB 110 transmits an ePDCCH for which one or more PUCCHresources are to be allocated. In some examples, the eNB 110 determinesa position (e.g. an eCCE index) at which it will transmit the ePDCCH.The eNB 110 then transmits the ePDCCH at the determined position.

An example operation 1900 of the example processes 1700 and 1800implementing example solution #4 in which the position of an ePDCCH ismapped to a PUCCH resource using PUCCH resource remapping is illustratedin FIG. 19. Somewhat different from hybrid implicit/explicit resourceallocation (e.g., solution #1) and extended implicit resource allocation(e.g., solution #2), a scaled resource index (also referred to herein asa scaled index) is calculated instead of a normalized resource index insolution #4. In some examples, the scaled resource index is calculatedas └k/L₀┘, using the index of the first eCCE of a UE's ePDCCH (‘k’) andthe number of CCE groups (‘L₀’). In some examples, the CCE group numberis equivalent to a PUCCH resource allocation group described in greaterdetail below, and is indicated in FIG. 19 as n _(PUCCH)=mod(k, L₀). Insolution #4, the CCE group number (or PUCCH resource allocation group)is computed from the resource index, and then remapped to a differentindex according to the CCE groups' probability of occurrence. Theremapped PUCCH resource group may be expressed as map(n _(PUCCH)). Inthe illustrated example operation 1900 of FIG. 19, an example remappingfunction is expressed as map(i)={0,2,1,3}, where map(i) indicateselement i in the list, starting with element 0. In the illustratedexample, the scaled resource index is then combined with the remappedgroup index and the ePDCCH's MU-MIMO layer (‘k′’) using a group scalefactor, which can be expressed as

$\left\lfloor \frac{k}{L_{0}} \right\rfloor + {\left( {{{map}\left( {\overset{\_}{n}}_{PUCCH} \right)} + k^{\prime}} \right){G.}}$

The group scale factor, G, is assumed to be G=2 in the example of FIG.19. The combined result is then further combined with a PUCCH resourceoffset, N_(ePUCCH) ⁽¹⁾(u,n_(type)), to produce the allocated PUCCHresource, where u is the index of the UE. The allocated PUCCH resourcefor UE u is indicated as n_(PUCCH,UEu) ⁽¹⁾ in the example of FIG. 19.

Further details concerning example solution #4, which corresponds toPUCCH resource allocation utilizing PUCCH resource remapping are nowprovided. As described above, some PUCCH resources are more frequentlyoccupied than others when the position of an ePDCCH (e.g., the lowesteCCE index used to construct the ePDCCH) is used to determine the PUCCHresource. This behavior can be used to reduce the amount of PUCCHresources required in an LTE system, such as the system 100. Forexample, if the PUCCH mapping is changed such that the most frequentlyoccupied eCCE groups map to small PUCCH resource indices, PUCCH PRBscorresponding to high PUCCH resource indices will be infrequentlyoccupied. Therefore, a smaller amount of total PUCCH resource can beused. For example, using the occupation probabilities associated withthe example operation 1900 of FIG. 19, eCCE groups can be ordered indecreasing order of probability as n _(CCE)=0, n _(CCE)=2, n _(CCE)=1,and n _(eCCE)=3. In some example, mapping function and the permutingused in the PUCCH remapping procedure can be more generally describedusing Equation 16:

$\begin{matrix}{n_{{PUCCH},i}^{({p = p_{j}})} = {\left\lfloor \frac{k}{L_{0}} \right\rfloor + {\left( {{{map}\left( {\overset{\_}{n}}_{PUCCH} \right)} + \delta_{i,j} + k^{\prime}} \right) \cdot G} + {N_{ePUCCH}^{(1)}\left( {u,n_{type}} \right)}}} & {{Equation}\mspace{14mu} 16}\end{matrix}$

Equation 16 includes the following parameters:

n_(PUCCH,i) ^((1,p=p) ^(j) ⁾ is the i^(th) PUCCH resource the UE maytransmit on antenna port p_(j), as described in Equation 10;

k is an integer that identifies the location of an ePDCCH containing adownlink grant to the UE, or that identifies the location of a PDSCHtransmission containing data for the UE;

k′ is an integer that identifies an antenna port and/or an MU-MIMO layerof an ePDCCH containing a downlink grant to the UE. If k′ is not needed(such as when MU-MIMO is not used on ePDCCH), it can be omitted, orequivalently set to 0. (Note that the variable k′ is used in the examplesolution #4 to replace the variable m used in example solutions #1 and#2 in order to be consistent with LTE usage for TDD that is referencedin this solution);

L₀ is a number of PUCCH resource groups. An example value may be L₀=4.In some examples, L₀ can be chosen to be a multiple of, or equal to, theaggregation levels of the ePDCCHs. For example, if L₀=4, it is amultiple of aggregation levels 1, 2, and equal to aggregation level 4.Another suitable value may be L₀=8, as then all LTE Rel-10 aggregationlevels are submultiples or equal to L₀;

n _(PUCCH)=mod(k, L₀) is an index of a PUCCH resource allocation group.In some examples, the PUCCH resource allocation groups can be eCCEgroups, in which case n _(PUCCH)≡n _(CCE)≡mod(n_(eCCE),L₀);

map( ) is a remapping function that permutes group indices according tooccupation probability. For example, the elements of map( ) can beordered such that higher indexed elements have lower occupationprobability. The function map(i) indicates element i in the list,starting with element 0. Furthermore, map( ) is a one to one mappingwherein each i corresponds to a single, unique, map(i). For example, ifL₀=4, an example choice for the mapping function may bemap(i)={0,2,1,3}. In this example, map(1)=2. The values shown areexemplary, and others may be used;

G is an integer used to allow PUCCH resource groups to be mapped fartherapart in PUCCH resources. One example value may be

$G = {\left\lfloor \frac{N_{eCCE}}{L_{0}} \right\rfloor.}$

where N_(eCCE) is a number of eCCEs in a subframe;

N_(ePUCCH) ⁽¹⁾(u,n_(type)) u, δ_(i,j), and n_(type) may be defined andused as in extended implicit resource allocation, including as inEquation 8 and Equation 10.

In some examples, the location identifier, k, may be globally defined,wherein when a value of k is used by any UE, it refers to the samephysical resource on ePDCCH or PDSCH. One approach for globally definingk is to have k=0 correspond to the beginning of resources in which anyePDCCH or PDSCH can be scheduled, and increasing values of k continueuntil the end of the ePDCCH or PDSCH resources. Equation 16 above issuitable for use with such a globally defined k.

If an index of an ePDCCH or PDSCH is UE specifically defined such that avalue of k used by any UE may not refer to the same ePDCCH or PDSCHphysical resource, an alternative disclosed example can be used whereink is shifted to align the resource groups such that good resource groupconcentration is maintained. For example, this can be achieved usingEquation 17 below:

$\begin{matrix}{n_{{PUCCH},j}^{({p = p_{j}})} = {\left\lfloor \frac{k + {N_{k}\left( {u,n_{type}} \right)}}{L_{0}} \right\rfloor + {\left( {{{map}\left( {\overset{\_}{n}}_{PUCCH}^{\prime} \right)} + \delta_{i,j} + k^{\prime}} \right) \cdot G} + {N_{ePUCCH}^{(1)}\left( {u,n_{type}} \right)}}} & {{Equation}\mspace{14mu} 17}\end{matrix}$

In Equation 17, the variables as defined for Equation 16 are the same,and Equation 17 also includes the following parameters:

n′_(PUCCH)≡mod(k+N_(k)(u,n_(type)),L₀) is an index of a shifted PUCCHresource allocation group. It is an extension of n _(PUCCH) that alignsa UE specifically defined k with ePDCCH or PDSCH physical resources;

N_(k)(u,n_(type)) is an integer resource offset that shifts betweenresource allocation groups, and may be in the range0≦N_(k)(u,n_(type))<L₀. Note that because N_(ePUCCH) ⁽¹⁾(u,n_(type)) maybe UE specific, it can be adjusted to align a UE specifically defined kwith ePDCCH or PDSCH physical resources by more than L₀. Consequently,larger values of N_(k)(u,n_(type)) may not be needed. One way todetermine N_(k)(u,n_(type)) is to set n′_(PUCCH) to correspond to themost probable ePDCCH or PDCCH resource group. N_(k)(u,n_(type)) is usedfor a UE with index u scheduled on an ePDCCH transmission type indexedby n_(type). In some examples, N_(k)(u,n_(type)) may be common to allUEs on a cell. In such examples, a single value of N_(k)(u,n_(type)) isused for all UEs, that is, N_(k)(u,n_(type))=N_(k)(0,n_(type)) for allUE indices U. If N_(k)(u,n_(type)) may be different for each UE, it cansignaled to UEs with, for example, UE specific RRC signaling. Also, insome example, N_(k)(u,n_(type)) may not be a function of n_(type), whichis equivalent to N_(k)(u,n_(type))=N_(k)(u,0).

In some examples of PUCCH resource remapping, a PUCCH resource isdetermined using the resource position and the DMRS configuration of theePDCCH transmitted to the UE. In such examples, k=n_(eCCE), wheren_(eCCE) is the location of the ePDCCH in ePDCCH resources. For example,n_(eCCE) may be an index of one of the eCCEs (such as the first or lasteCCE) of the ePDCCH transmitted to the UE.

Some examples of solution #4 may support enhanced resource allocationfor LTE Rel-10 PDCCH, in which case k=n_(eCCE), where n_(eCCE) is thelocation of the PDCCH in PDCCH resources, and may be the first CCE ofthe PDCCH. Because MU-MIMO or DM-RS are not used for PDCCH reception, inthis case, k′ is not used, and is equivalently set to k′=0 in Equation16.

In some examples, k′=n_(DMRS). The variable n_(DMRS) may be an index ofa DMRS configuration used in a successful decode of a ePDCCH located atn_(eCCE). For example, the DMRS configuration can be a combination ofscrambling index and antenna port. It is possible that the combinationsof scrambling index or antenna port could be fixed in futurespecifications or signaled with RRC signaling, and that either or bothof the scrambling index or antenna port would be fixed to a single valuefor a UE.

In some examples, it may be desirable to index the values of k′ in orderof increasing likelihood of use. If the most frequent values of k′ aresmall, then low PUCCH resources are used, thereby allowing less PUCCHresources to be allocated. This indexing may require extra care when anantenna port may be associated with an eCCE. Because eCCE groups canhave different occupancy probabilities, then the corresponding antennaports may have different occupancy probabilities. If an ePDCCH isfrequently received with an antenna port tied to a lightly occupiedePDCCH group, it may be frequently mapped to high PUCCH resources. Itmay therefore be desirable to allow each UE to use a different mappingof k′ to antenna port and/or ePDCCH MIMO layer, such that each UE'svalues of k′ can be indexed in order of increasing likelihood of use forthat UE.

FIG. 20 illustrates how remapping can concentrate the used PUCCHresources. In FIG. 20, the ‘Rel-8’ curve 2005 depicts the probabilitythat a PUCCH resource is occupied using LTE Rel-8 PUCCH mechanisms,while the ‘Remapped’ curve 2010 depicts the results when the PUCCHresources are reordered according to solution #4 disclosed herein. Inthe illustrated example of FIG. 20, the heavily occupied Rel-8 PUCCHresources are distributed evenly across the available PUCCH resource.After remapping (e.g., corresponding to curve 2010), it can be seen thatthe heavily occupied PUCCH resources are concentrated in the first 10resources, the next 10 resources are significantly occupied, and thelast 20 are infrequently used.

In some examples, PUCCH resource allocation according to solution #4 canfurther modified for TDD operation to concentrate eCCEs in a smallernumber of eCCE groups. Implicit PUCCH resource mapping is determined inLTE Rel-10 using Equation 18 and Equation 19 below, where the equationsand their variables are defined in 3GPP TS 36.213, V10.1.0.

n _(PUCCH) ^((1,{tilde over (p)}) ¹ ⁾⁼⁽ M−m−1)·N _(c) +m·N _(c+1) +n_(CCE) +N _(PUCCH) ⁽¹⁾   Equation 18

N _(c)=max{0,└[N _(RB) ^(DL)·(N _(sc) ^(RB) ·c−4)]/36┘}  Equation 19

When multiple TDD DL subframes must be Ack/Nack'd, the values of N_(c)tend not to be multiples of an aggregation level, and so are spreadamong eCCE groups more than for FDD. Note that Equation 18 uses thevariable m as defined in 3GPP TS 36.213, V10.1.0, rather than as in theother example solutions disclosed herein.

An example approach for improving eCCE group concentration over the CCEgroup concentration in LTE Rel-8 is to force N_(c) to be a multiple ofL₀. This can be accomplished by modifying the definition of N_(c) fromEquation 19 to be:

N _(c)=max{0, L ₀·┌(└[N _(RB) ^(DL)·(N _(sc) ^(RB) ·c−4)]/36┘/L₀)┐}  Equation 20

In Equation 20, ┌x┐ is the smallest integer larger than or equal to thereal number x.

An example PUCCH resource occupancy for LTE TDD configuration 1 is shownin the FIG. 21 with and without the modified N_(c). As can be seen fromthe figure, the modified version (e.g., corresponding to example curve2110) produces a ‘spikier’ PDF, and has better CCE group concentration,than LTE Rel-8 (e.g., corresponding to example curve 2105).

The amount of required PUCCH resources for TDD can vary with the numberof downlink subframes being Ack/Nack'd in an uplink subframe.Consequently, it may not be desirable to reorder PUCCH resourcesaccording to the maximum number of PUCCH resources that could berequired in a subframe. Instead, in some examples, a block-basedreordering approach may be used. Such a PUCCH remapping procedurecustomized for TDD can be described using the following equation:

$\begin{matrix}{n_{{PUCCH},i}^{({1,{p = p_{j}}})} = {\left\lfloor \frac{{\overset{\sim}{n}}_{PUCCH}}{L_{0}} \right\rfloor + {\left( {{{map}\left( {\overset{\_}{n}}_{PUCCH} \right)} + \delta_{i,j} + k^{\prime}} \right) \cdot G} + {N_{eCCE}^{\max} \cdot \left\lfloor \frac{{\overset{\sim}{n}}_{PUCCH}}{N_{eCCE}^{\max}} \right\rfloor} + {N_{ePUCCH}^{(1)}\left( {u,n_{type}} \right)}}} & {{Equation}\mspace{14mu} 21}\end{matrix}$

In Equation 21, the variables as defined for Equation 16 are the same,and Equation 21:

n _(PUCCH)≡mod(ñ_(PUCCH),L₀) is an index of a PUCCH resource allocationgroup implicitly derived from a resource index, such as an eCCE index;

ñ_(PUCCH) is an intermediate PUCCH resource allocation value. It canrepresent the PUCCH resource that is allocated by Rel-10 LTE, butwithout PUCCH resource shifts such as N_(PUCCH) ⁽¹⁾. In some examples,ñ_(PUCCH)=(M−m−1)·N_(c)+m·N_(c+1)+n_(CCE);

N_(CCE) ^(max) is a maximum number of eCCEs in any subframe.

In some examples, a desirable value for G may be

$G = {\left\lfloor \frac{N_{eCCE}^{\max}}{L_{0}} \right\rfloor.}$

An example PUCCH resource occupancy for LTE TDD configuration 1 is shownin FIG. 22 with the modified remapping (e.g., corresponding to examplecurve 2210) and without the modified remapping (e.g., corresponding tothe example curve 2205). The block-based remapping produces two regionswhere PUCCH resource occupancy is heavily concentrated, rather than oneas in FIG. 20. This corresponds to the need to Ack/Nack up to two DLsubframes in configuration 1. While there are now two regions of lowoccupancy (e.g. PUCCH resources 22-44 and 66-88), the total amount oflow occupancy is still approximately the same: about half the PUCCHresources. PUCCH resources 66-88 could be unscheduled, and potentiallyused for PUSCH fairly easily, as they could border the PUSCH region. ThePUCCH resources 22-44 could potentially be reused for about 1 PRB ofPUSCH (since 18 PUCCH resources are typically mapped to one PRB),although this may be less beneficial as it is surrounded by PUCCH PRBs.Therefore, using example solution #4, it may be possible to improvePUCCH resource efficiency by about 25%, and up to possibly a 50%efficiency gain.

A fifth example UE process 2300 that may be executed to implement theexample UE UCC resource allocator 125 of FIG. 1 is illustrated in FIG.23. A corresponding fifth example eNB process 2400 that may be executedto implement the example eNB UCC resource allocator 130 of FIG. 1 isillustrated in FIG. 24. The fifth example processes 1700 and 1800implement a fifth example solution (also referred to herein as examplesolution #5) disclosed herein for performing PUCCH resource allocationfor an ePDCCH. Example solution #5 corresponds to PUCCH resourceallocation using a dynamic PUCCH offset indication, which may besignaled to the UE 105 in DCI.

In example solution #5, a UE (e.g., the UE 105) scheduled through ePDCCHcan use a dynamic PUCCH offset indication provided in DCI to determinePUCCH resources for TDD when, for example, the number of eCCEs in anePDCCH set varies by subframe and/or between ePDCCH sets, and/or thenumber of monitored eCCEs is zero and PDCCH is instead monitored.

In LTE Rel-11, a UE may be configured to monitor multiple ePDCCHresource regions (also referred to as ePDCCH sets) that are configured(e.g., semi-statically) for that UE. When a UE receives an ePDCCH in anePDCCH set, the UE determines an eCCE index from the position of theePDCCH in the ePDCCH set. The position of the ePDCCH is defined by thefirst eCCE that the ePDCCH occupies. The eCCE index is a non-negativeinteger, where an index of 0 for an ePDCCH set corresponds to the firsteCCE in the ePDCCH set.

A Rel-11 FDD UE may determine the PUCCH resources from the eCCE indexderived from the ePDCCH set in which it receives ePDCCH according to thefollowing equation:

n _(PUCCH) ⁽¹⁾=Δ_(ARO) +f(n _(eCCE) ,p)+N _(PUCCH,j) ⁽¹⁾   Equation 22

Equation 22 includes the following parameters:

Δ_(ARO)={−2,−1,0,2} and is a dynamic PUCCH Ack/Nack resource offset(ARO) indicated to the UE in, for example, DCI carried by ePDCCH;

N_(PUCCH,j) ⁽¹⁾ is a PUCCH resource offset associated with ePDCCH setwith index ‘j’;

and f (n_(eCCE,)p) is determined for localized and distributed ePDCCH,respectively, using the following equation:

$\begin{matrix}{{f\left( {n_{eCCE},p} \right)} = \left\{ \begin{matrix}{\mspace{14mu} {{Localized}\text{:}}} & {{\left\lfloor {n_{{eCCE},j}\text{/}N} \right\rfloor \cdot N} + k_{p}} \\{{Distributed}\text{:}} & n_{{eCCE},j}\end{matrix} \right.} & {{Equation}\mspace{14mu} 23}\end{matrix}$

Equation 23 includes the following parameters:

n_(eCCE,j) is the index of the first eCCE of an ePDCCH transmission inthe ePDCCH set with index j;

N is the number of eCCEs per PRB;

k_(p) is determined from DMRS port used to demodulate ePDCCH.

In some examples, k_(p)={0,1,2,3} if N=4, and k_(p)={0,1} if N=2.

Furthermore, it was agreed that in LTE Rel-11 for TDD, the PUCCHresource is to also depend on the following quantity:

$\begin{matrix}{\sum\limits_{i = 0}^{m - 1}\; N_{{eCCE},i,j}} & {{Equation}\mspace{14mu} 24}\end{matrix}$

Equation 24 includes the following parameters:

N_(eCCE,i,j) is equal to the number of eCCEs in subframe i in the ePDCCHset j configured for that UE; and

m=(0 . . . M-1) is the relative index of the DL subframe of the PDSCHscheduled by ePDCCH.

The number of eCCEs in subframe i in ePDCCH set j can be determinedusing any appropriate known or future technique. In some examples, thenumber of eCCEs in an ePDCCH set is equivalently identified asN_(ECCE,m,i) for an ePDCCH set with ePDCCH set index m in subframe i,and can be calculated using ePDCCH format information such as isprovided in 3GPP TS 36.211 section 6.8A.1. 3GPP Technical Specification(TS) 36.211, Version 11.1.0 (Dec. 20, 2012) is hereby incorporated byreference in its entirety.

The value of the parameter k_(p) can be determined using any appropriateknown or future technique. In some examples, this parameter can beequivalently defined as n′ as it is used in section 6.8A.5 of 3GPP TS36.211, Version 11.1.0.

The agreement reflected in Equation 24 does not fully specify how PUCCHresource should be calculated for TDD UEs receiving ePDCCH. If Equation22 is used as the basis for resource allocation, it has not beenpreviously decided how Equation 24 is used in that context. Therefore,example solution #5 provides example techniques to calculate PUCCHresources for TDD UEs receiving ePDCCH and using a PUCCH resource offsetdynamically signaled through DCI.

In one such example of solution #5, Equation 25 and Equation 26 are usedto perform PUCCH resource allocation for TDD UEs receiving ePDCCH andusing a PUCCH resource offset dynamically signaled through DCI. Equation25 can be used by a UE (e.g., the UE 105) and an eNB (e.g., the eNB 110)to respectively calculate a sum of offsets given by:

n _(PUCCH,l) ⁽¹⁾=Δ_(ARO)(n−k _(i))+f(n _(eCCE,m,j) ,n′)+N _(PUCCH,j) ⁽¹⁾+N _(T)(n,j ₀)   Equation 25

Equation 25 includes the following parameters:

n_(PUCCH,l) ⁽¹⁾ is the i^(th) PUCCH resource index that is to beallocated to the UE (e.g., the UE 105) in subframe n. It corresponds toa DL grant received at subframe In some examples, if an ePDCCH or PDCCHis not received in subframe n-k_(i), and the UE (e.g., the UE 105) doesnot determine (e.g. from higher layer signaling) that a PDSCH isscheduled for it in subframe n-k_(i), the corresponding n_(PUCCH,l) ⁽¹⁾is not defined;

Δ_(ARO)(n-k_(i)) is a dynamic PUCCH Ack/Nack resource offset (ARO)indicated in the downlink grant in subframe n-k_(i). An example set ofoffset values to use is Δ_(ARO)={−2,−1,0,2};

f(n_(eCCE,m,j),n′) is an implicit component of the PUCCH resourceindication. It may be calculated using n_(eCCE,m,j) and/or n′ discussedabove. For example, f(n_(eCCE,m,j),n′) may be calculated using Equation23;

n_(eCCE,m,j) is the index of the first eCCE of an ePDCCH received by theUE in the ePDCCH set with index j in the subframe that corresponds tothe relative index m;

N_(PUCCH,j) ⁽¹⁾ is the PUCCH resource offset associated with an ePDCCHreceived by the UE, where the ePDCCH is in an ePDCCH set having index‘j’;

N_(T)(n,j₀) is a subframe offset that offsets the PUCCH resourcecorresponding to different DL subframes.

Equation 26 is given by:

$\begin{matrix}{{N_{T}\left( {n,j_{0}} \right)} = {\sum\limits_{i = 0}^{m - 1}\; {g\left( N_{{eCCE},{n - k_{i}},j_{0}} \right)}}} & {{Equation}\mspace{14mu} 26}\end{matrix}$

Equation 26 includes the following parameters:

n is the subframe index in which the PUCCH resource is to be computed(e.g., allocated);

m=(0 . . . M-1) is the relative index of the DL subframe of the PDSCHscheduled by ePDCCH in subframe n;

j₀ is an index of the ePDCCH set used to compute a number of eCCEs,N_(eCCE,n-k) _(i) _(,j) ₀ , defined below. Example techniques todetermine j₀ are described below. Note that, in some examples, j₀ can bedifferent from j;

N_(eCCE,n-k) _(i) _(,j) ₀ is equal to the number of eCCEs in an ePDCCHset with index j₀ in a subframe with index n-k_(i) in which a downlinkgrant for the UE may be detected. In some examples, N_(eCCE,n-k) _(i)_(,j) ₀ is calculated by the UE according to parameters provided by RRCsignaling;

k_(i) is an integer constant that is an element of {k₀,k₁, . . .k_(M-1)};

M is the number of elements in a downlink association set index K.

For example, the variables m, M, n, K, and {k₀,k₁, . . . k_(M-1)} can bedetermined as they are for LTE TDD HARQ-ACK feedback procedures, such asdescribed in section 10.1.3 of 3GPP TS 36.213, V10.1.0.

In Equation 26, g( ) is a function that produces a PUCCH resource offsetvalue for subframe n, as further described herein. In some examples, avalue for g( ) may be calculated for every subframe that the UE monitorsePDCCH or PDCCH, independently of if the UE is scheduled in thatsubframe.

Equation 25 and Equation 26 depend on determining the ePDCCH set j₀. Oneexample way to determine this subset would be to use the ePDCCH set inwhich the UE receives an ePDCCH, in other words, set j=j₀ in Equation 25and Equation 26. However, if the UE misses the ePDCCH, it may not knowwhich ePDCCH set index j₀ to use to determine N_(eCCE,n-k) _(i) _(,j) ₀. Furthermore, for TDD, N_(eCCE,n-k) _(i) _(,j) ₀ can be different innormal subframes and in special subframes, and so determining the ePDCCHset to use may be insufficient to determine N_(eCCE,n-k) _(i) _(,j) ₀ inall subframes. Similar problems do not exist in LTE Rel-10, since, asdescribed in section 10.1.3 of 3GPP TS 36.213, Rel-10 TDD implicit PUCCHresource allocation is calculated using the PDCCH CCE index, on therelative subframe index m, and on a PUCCH resource offset N_(PUCCH) ⁽¹⁾that does not vary as a function of the subframe. Given these issues,other examples discussed hereinbelow do not determine the ePDCCH set j₀as the set in which ePDCCH is received.

Because N_(eCCE,n-k) _(i) _(,j) ₀ can vary with the subframe index n andbetween ePDCCH sets with different indices j, example techniques forsolution #5 yielding a function g( ) to map N_(eCCE,n-k) _(i) _(,j) ₀ toa single value for different values of n and j are disclosed. Multipleexample alternatives exist for determining the index j₀ and for how g( )should behave as a function of the subframe n, as described below.

The following are two such example techniques to determine the ePDCCHset index j₀ for example solution #5. The techniques differ on whetherthe numbers of eCCEs in the ePDCCH sets are used to determine the set orwhether such numbers are not used.

EXAMPLE TECHNIQUE 1 FOR SOLUTION #5 Fixed j₀

In this first example technique, j₀ does not depend on the number ofeCCEs in the ePDCCH sets, so a predetermined value for j₀ may be used,and then

${N_{T}(n)} = {\sum\limits_{i = 0}^{m - 1}\; {N_{{eCCE},{n - k_{i}},j_{0}}.}}$

In some examples, this predetermined value may be a single index fixedin a physical layer specification, such as j₀=0, which may correspond tothe first configured ePDCCH set when the UE is sent a message withePDCCH set configuration information. When the message is an RRCmessage, such as is defined in 3GPP TS 36.331 V11.2.0 (December 2012),which is incorporated herein by reference in its entirety, j₀ maycorrespond to an epdcch-SetIdentity in an EPDCCH-SetConfig informationelement, and the predetermined value of j₀=0 may correspond to anepdcch-SetIdentity=0. In other examples, the predetermined value may bethe minimum value of epdcch-SetIdentity of the ePDCCH sets configuredfor the UE. In such examples, each epdcch-SetIdentity may be containedin an EPDCCH-SetConfig that configures the corresponding ePDCCH set, andthe configured sets for a UE may be added or modified using anEPDCCH-SetConfigAddModList. In still other examples, the predeterminedvalue may be the minimum value of an ePDCCH set index for which anePDCCH set has been configured. For example, when the ePDCCH sets areindexed using an index q, as in 3GPP TS 36.213, V11.1.0 (Dec. 20, 2012),which is incorporated herein by reference in its entirety, section 10.1,and two ePDCCH sets have been configured that are indexed by q=0 andq=1, the predetermined value could be j₀=min({0,1})=0. However, if onlyone ePDCCH set is defined with index q=0 or q=1, the predetermined valuecould be j₀=min({0})=0 or j₀=min({1})=1, respectively.

EXAMPLE TECHNIQUE 2 FOR SOLUTION #5 j₀ is Derived from ePDCCH Set Size

In this second example technique, the ePDCCH set index j₀ could bedetermined as the index j corresponding to the ePDCCH set with thelargest N_(eCCE,n-k) _(i) _(,j) that could occur in subframe n-k_(i).For example, the equation

$j_{0} = {\underset{j}{\arg \mspace{14mu} \max}\left( N_{{eCCE},{n - k_{i}},j} \right)}$

may be used for this purpose, and so

${N_{T}\left( {n,j_{0}} \right)} = {\sum\limits_{i = 0}^{m - 1}\; {\max\limits_{j_{0}}{\left( N_{{eCCE},{n - k_{i}},j_{0}} \right).}}}$

The values of N_(eCCE,n-k) _(i) _(,j) used to compute the largestN_(eCCE,n-k) _(i) _(,j) can be determined, for example, using the numberof enhanced resource element groups (EREGs) in an eCCE in the subframe,such as is defined in 3GPP TS 36.211, V11.1.0, section 6.8A.1.

Comparing the preceding two example techniques for determining theePDCCH set index j₀, the predetermined value may have the benefit ofsimplifying the N_(eCCE,n-k) _(i) _(,j) calculation in the UE 105 andthe eNB 110. When the predetermined value is determined as a firstconfigured ePDCCH set, a second benefit can be to allow more or lessPUCCH resources to be used. Because the amount of resource used by a UEis larger if N_(T)(n,j₀) is larger, and using a set with the largest orthe smallest value of N_(eCCE,n-k) _(i) _(,j) will make N_(T)(n,j₀)larger or smaller, respectively, more or less PUCCH resources can beused depending on if the first configured ePDCCH set is the one with thelargest or smallest value of N_(eCCE,n-k) _(i) _(,j). On the other hand,a benefit of using a value depending on the number of eCCEs in theePDCCH sets, such as the largest N_(eCCE,n-k) _(i) _(,j), could be toallow the amount of allocated PUCCH resource to better track the needaccording to the downlink control overhead on ePDCCH. Furthermore, usingthe largest N_(eCCE,n-k) _(i) _(,j) instead of a smaller value may helplimit how often the same PUCCH resource is associated with differentePDCCHs, thereby allowing more efficient scheduling of ePDCCH.

EXAMPLE TECHNIQUE 3 FOR SOLUTION #5 Using Constant g( )

In a third example technique for solution #5, the function g( ) isconstant over all subframes n. In this example, the UE may determine amaximum value of N_(eCCE,n-k) _(i) _(,j) for ePDCCH set j for anysubframe i according to its configured ePDCCH set(s), and use themaximum value of N_(eCCE,n-k) _(i) _(,j) to calculate

${{N_{T}\left( {n,j_{0}} \right)} = {\sum\limits_{i = 0}^{m - 1}\; {g\left( N_{{eCCE},{n - k_{i}},j_{0}} \right)}}},$

which may be expressed with N_(T)(n,j₀)=m·N_(eCCE,j) ₀ ^(max); where

${{g\left( N_{{eCCE},i,j} \right)} = {N_{{eCCE},j}^{\max} = {\max\limits_{i}\left( N_{{eCCE},i,j} \right)}}},$

and where j₀ is an index of an ePDCCH set configured for the UE. The UEmay determine N_(eCCE,i,j) using the number of EREGs in an eCCE in asubframe i, such as is defined in 3GPP TS 36.211, V11.1.0, section6.8A.1. In some examples, a fixed value may be used for j₀ such as thatdescribed in example technique 1 above. In other examples, the ePDCCHset index j₀ can correspond to an ePDCCH set configured for the UE withthe largest N_(eCCE,j) ^(max), and so in such an example,

${N_{T}\left( {n,j_{0}} \right)} = {{N_{T}(n)} = {m \cdot {\max\limits_{j}{\left( N_{{eCCE},j}^{\max} \right).}}}}$

If a UE (e.g., the UE 105) monitors PDCCH in subframe n-k_(i) (andtherefore may not monitor ePDCCH), Equation 25 and Equation 26 may stillbe used to compute n_(PUCCH,l) ⁽¹⁾ for other subframes where the UEmonitors ePDCCH, except that N_(T)(n,j₀) may be calculated differentlywhen the UE only receives ePDCCH. In one such example, if the UE doesnot receive ePDCCH in subframe n-k_(i), the number of eCCEs the UEreceives is 0, and so g(N_(eCCE,n-k) _(i) _(,j) ₀ ) is set asg(N_(eCCE,n-k) _(i) _(,j) ₀ )=0 when calculating N_(T)(n,j₀). In anotherexample for calculating N_(T)(n,j₀) corresponding to when PDCCH ismonitored in subframe n-k_(i), the index j₀ could be determined(similarly to when it only receives ePDCCH) as the index j correspondingto the ePDCCH set with the largest N_(eCCE,n-k) _(i) _(,j) that couldoccur in subframe n-k_(i), and the equations

$j_{0} = {\underset{j}{\arg \mspace{14mu} \max}\left( N_{{eCCE},{n - k_{i}},j} \right)}$

and

${N_{T}\left( {n,j_{0}} \right)} = {{N_{T}(n)} = {\sum\limits_{i = 0}^{m - 1}\; {\max\limits_{j_{0}}\left( N_{{eCCE},{n - k_{i}},j_{0}} \right)}}}$

may be used. In an alternative example corresponding to when PDCCH ismonitored in subframe n-k_(i), the UE may determine a maximum value ofN_(eCCE,n-k) _(i) _(,j) ₀ , for example using N_(T)(n,j₀)=m·N_(eCCE,j) ₀^(max) with N_(eCCE,j0) ^(max)=max(N_(eCCE,n-k) _(i) _(,j) ₀ ) In suchan example, a predetermined value for j₀ may be used, and so

${N_{T}\left( {n,j_{0}} \right)} = {m \cdot {\max\limits_{i}{\left( N_{{eCCE},i,j_{0}} \right).}}}$

This predetermined value may be a single index fixed in a futurephysical layer specification, such as j₀=0, which may correspond to thefirst configured ePDCCH set when the UE is sent a message with ePDCCHset configuration information.

If a UE monitors PDCCH in subframe n-k_(i), PDCCH may not carry anindicator of a dynamic PUCCH Ack/Nack resource offset (ARO).Furthermore, there may be no DMRS port used to receive PDCCH, and sodifferent treatment with respect to the variable n′ may be involved.However, in such examples, LTE Rel-10 PUCCH resource allocationtechniques may still be suitable. Therefore, in some examples, when a UEmonitors PDCCH in subframe n-k_(i), the UE determines the correspondingPUCCH resource for that subframe as is defined in LTE Rel-10 in section10.1.3 of TS 36.213, V10.1.0 for TDD, and as provided by Equation 18 andEquation 19 above. In such examples, n_(PUCCH,l) ⁽¹⁾ can be determineddifferently according to l. Furthermore, for l corresponding to subframen-k_(i), in which ePDCCH is monitored, in such examples Equation 25 andthe modified calculation of N_(T)(n,j₀) discussed in the precedingparagraph can be used to) compute n_(PUCCH,l) ⁽¹⁾. For l correspondingto subframe n-k_(i), in which PDCCH is monitored, the LTE Rel-10 methodsare used to compute n_(PUCCH,l) ⁽¹⁾.

In some examples, it may be desirable for the UE (e.g., the UE 105) totransmit PUCCH only on resources associated with ePDCCH even though itmonitors PDCCH. In such examples, Equation 25 can be modified todetermine n_(PUCCH,l) ⁽¹⁾ for l corresponding to subframe n-k_(i) inwhich the UE monitors PDCCH, as shown in the following equation:

n _(PUCCH,l) ⁽¹⁾ =f(n _(CCE,m))+N _(PUCCH,j) ₀ ⁽¹⁾ +N _(T)(n,j ₀)  Equation 27

Equation 27 includes the following parameters:

n_(PUCCH,l) ⁽¹⁾ is the l^(th) PUCCH resource index. In some examples, ifan ePDCCH or PDCCH is not received in subframe n-k, and the UE does notdetermine (e.g. from higher layer signaling) that a PDSCH is scheduledfor it in subframe n-k_(i), the corresponding n_(PUCCH,l) ⁽¹⁾ is notdefined;

f(n_(CCE,m)) is an implicit component of the PUCCH resource indication.It may be calculated using n_(eCCE,m). One example way to computef(n_(CCE)) is f(n_(CCE,m))=n_(CCE,m);

n_(CCE,m) is the index of the first CCE of a PDCCH received by the UE inthe subframe that corresponds to the relative index m;

N_(PUCCH,j) ₀ ⁽¹⁾ is the PUCCH resource offset associated with a ePDCCHset having index ‘j₀’. In some examples, this set index may bepredetermined as a single index fixed in a future physical layerspecification, such as j₀=0, which may correspond to the firstconfigured ePDCCH set when the UE is sent a message with ePDCCH setconfiguration information. In other examples, j₀ could be determined asthe j corresponding to the ePDCCH set with the largest N_(eCCE,n-k) _(i)_(,j) that could occur in subframe n-k_(i), and the equation

$j_{0} = {\underset{j}{\arg \mspace{14mu} \max}\left( N_{{eCCE},{n - k_{i}},j} \right)}$

is used. In yet other examples, a largest N_(eCCE,i,j) that could occurin any ePDCCH set configured for the UE in any subframe i is used, whichmay be described as

${N_{{PUCCH},j_{0}}^{(1)} = {N_{eCCE}^{\max} = {\max\limits_{i,j}\left( N_{{eCCE},i,j} \right)}}};$

N_(T)(n,j₀) may be calculated as described above for when a UE monitorsPDCCH in subframe n-k_(i).

With the foregoing in mind, and with reference to the preceding figuresand associated descriptions, the example process 2300 of FIG. 23 beginsexecution at block 2305 at which the UE UCC resource allocator 125 ofthe UE 105 obtains (e.g., via signaling from the eNB 110 and/or anyother manner) any uplink control channel allocation parameters to beused for performing PUCCH resource allocation. At block 2305, the UE UCCresource allocator 125 also obtains (e.g., via signaling from the eNB110 and/or any other manner) information specifying one or more ePDCCHsets configured for the UE 105, as described above. At block 2315, theUE 105 receives an ePDCCH transmission, for which one or more PUCCHresources are to be allocated, in one of the ePDCCH sets (e.g., j), asdescribed above. The ePDCCH transmission received by the UE 105 at block2315 indicates a dynamic PUCCH Ack/Nack resource offset (ARO), asdescribed above. At block 2320, the UE UCC resource allocator 125determines a position (e.g., the eCCE index, n_(eCCE,j)) of the receivedePDCCH transmission in the ePDCCH set (e.g., j), as described above.

As described in greater detail above, at block 2325, the UE UCC resourceallocator 125 determines a number of control channel elements (e.g.,N_(eCCE,n-k) _(i) _(,j) ₀ ) in a second one of the ePDCCH sets (e.g.,j₀). As noted above, the ePDCCH set used at block 2325 may be the sameas, or different from, the ePDCCH set in which the ePDCCH was receivedat block 2315. At block 2330, the UE UCC resource allocator 125determines a subframe offset (e.g., N_(T)(n,j₀)) based on the number ofcontrol channel elements (e.g., N_(eCCE,n-k) _(i) _(,j) ₀ ), asdescribed above (e.g., using Equation 26). At block 2335, the UE UCCresource allocator 125 processes the position determined at block 2320,the dynamic PUCCH Ack/Nack resource offset (ARO) indicated in block 2315and the subframe offset determined at block 2330, as described above(e.g., using Equation 25), to determine an allocated PUCCH resource. Atblock 2340, the UE 105 transmits on the allocated PUCCH resource.

Correspondingly, the example process 2400 of FIG. 24 begins execution atblock 2405 at which the eNB UCC resource allocator 130 of the eNB 110provides (e.g., via signaling and/or any other appropriate manner) tothe UE 105 any uplink control channel allocation parameters to be usedfor performing PUCCH resource allocation. At block 2405, the eNB UCCresource allocator 130 also provides (e.g., via signaling and/or anyother appropriate manner) the information specifying the one or moreePDCCH sets configured for the UE 105. At block 2410, the eNB transmitsan ePDCCH carrying an indication of the dynamic PUCCH Ack/Nack resourceoffset (ARO to be used by the UE 105 when performing PUCCH resourceallocation according to example solution #5. For example, the eNB 110determines the position (e.g. an eCCE index) at which it will transmitthe ePDCCH. The eNB 110 then transmits the ePDCCH at the determinedposition and carrying the indication of the ARO.

FIG. 25 is a block diagram of an example processing system 2500 capableof executing the processes of FIGS. 5, 6, 9, 10, 14, 15, 17, 18, 23and/or 24 to implement the mobile communication system 100, the UEdevice 105, the eNB 110, the UE UCC resource allocator 125 and/or theeNB UCC resource allocator 130 of FIG. 1. The processing system 2500 canbe, for example, a mobile device (e.g., a smartphone, a cell phone,etc.), a personal digital assistant (PDA), a server, a personalcomputer, an Internet appliance, a DVD player, a CD player, a digitalvideo recorder, a Blu-ray player, a gaming console, a personal videorecorder, a set top box, a digital camera, or any other type ofcomputing device.

The system 2500 of the instant example includes a processor 2512. Forexample, the processor 2512 can be implemented by one or moremicroprocessors and/or controllers from any desired family ormanufacturer.

The processor 2512 includes a local memory 2513 (e.g., a cache) and isin communication with a main memory including a volatile memory 2514 anda non-volatile memory 2516 via a link 2518. The link 1518 may beimplemented by a bus, one or more point-to-point connections, etc., or acombination thereof. The volatile memory 2514 may be implemented byStatic Random Access Memory (SRAM), Synchronous Dynamic Random AccessMemory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS DynamicRandom Access Memory (RDRAM) and/or any other type of random accessmemory device. The non-volatile memory 2516 may be implemented by flashmemory and/or any other desired type of memory device. Access to themain memory 2514, 2516 is controlled by a memory controller.

The processing system 2500 also includes an interface circuit 2520. Theinterface circuit 2520 may be implemented by any type of interfacestandard, such as an Ethernet interface, a universal serial bus (USB),and/or a PCI express interface.

One or more input devices 2522 are connected to the interface circuit2520. The input device(s) 2522 permit a user to enter data and commandsinto the processor 2512. The input device(s) can be implemented by, forexample, a keyboard, a mouse, a touchscreen, a track-pad, a trackball, atrackbar (such as an isopoint), a voice recognition system and/or anyother human-machine interface.

One or more output devices 2524 are also connected to the interfacecircuit 2520. The output devices 2524 can be implemented, for example,by display devices (e.g., a liquid crystal display, a cathode ray tubedisplay (CRT)), a printer and/or speakers. The interface circuit 2520,thus, can include a graphics driver card.

The interface circuit 2520 can also include a communication device, suchas a modem or network interface card, to facilitate exchange of datawith external computers via a network 2526 (e.g., an Ethernetconnection, a digital subscriber line (DSL), a telephone line, coaxialcable, a cellular telephone system, etc.).

The processing system 2500 can also include one or more mass storagedevices 2528 for storing machine readable instructions and data.Examples of such mass storage devices 2528 include floppy disk drives,hard drive disks, compact disk drives and digital versatile disk (DVD)drives.

Coded instructions 2532 corresponding to the instructions of FIGS. 5, 6,9, 10, 14, 15, 17, 18, 23 and/or 24 may be stored in the mass storagedevice 2528, in the volatile memory 2514, in the non-volatile memory2516, in the local memory 2513 and/or on a removable storage medium,such as a CD or DVD 2536.

As an alternative to implementing the methods and/or apparatus describedherein in a system such as the processing system of FIG. 25, the methodsand or apparatus described herein may be embedded in a structure such asa processor and/or an ASIC (application specific integrated circuit).

Also, as used herein, the term “node” broadly refers to any connectionpoint, such as a redistribution point or a communication endpoint, of acommunication environment, such as a network. Accordingly, such nodescan refer to an active electronic device capable of sending, receiving,or forwarding information over a communications channel. Examples ofsuch nodes include data circuit-terminating equipment (DCE), such as amodem, hub, bridge or switch, and data terminal equipment (DTE), such asa handset, a printer or a host computer (e.g., a router, workstation orserver). Examples of local area network (LAN) or wide area network (WAN)nodes include computers, packet switches, cable modems, digitalsubscriber line (DSL) modems, wireless LAN (WLAN) access points, etc.Examples of Internet or Intranet nodes include host computers identifiedby an Internet Protocol (IP) address, bridges, WLAN access points, etc.Likewise, examples of nodes in cellular communication include basestations, relays, base station controllers, radio network controllers,home location registers, Gateway GPRS Support Nodes (GGSN), Serving GPRSSupport Nodes (SGSN), Serving Gateways (S-GW), Packet Data NetworkGateways (PDN-GW), etc.

Other examples of nodes include client nodes, server nodes, peer nodesand access nodes. As used herein, a client node may refer to wirelessdevices such as mobile telephones, smart phones, personal digitalassistants (PDAs), handheld devices, portable computers, tabletcomputers, and similar devices or other user equipment (UE) that hastelecommunications capabilities. Such client nodes may likewise refer toa mobile, wireless device, or conversely, to devices that have similarcapabilities that are not generally transportable, such as desktopcomputers, set-top boxes, sensors, etc. A server node, as used herein,may refer to an information processing device (e.g., a host computer),or series of information processing devices, that perform informationprocessing requests submitted by other nodes. As used herein, a peernode may sometimes serve as a client node, and at other times, a servernode. In a peer-to-peer or overlay network, a node that actively routesdata for other networked devices as well as itself may be referred to asa supernode. An access node, as used herein, may refer to a node thatprovides a client node access to a communication environment. Examplesof access nodes include, but are not limited to, cellular network basestations such as evolved Node Bs (eNBs), wireless broadband (e.g., WiFi,WiMAX, etc) access points, etc., which provide corresponding cell and/orWLAN coverage areas, etc.

Finally, although certain example methods, apparatus and articles ofmanufacture have been described herein, the scope of coverage of thispatent is not limited thereto. On the contrary, this patent covers allmethods, apparatus and articles of manufacture fairly falling within thescope of the appended claims either literally or under the doctrine ofequivalents.

1-62. (canceled)
 63. A method in a user equipment (UE), comprising:receiving, at the UE, a downlink control channel carrying a physicaluplink control channel (PUCCH) resource indicator; mapping the PUCCHresource indicator to a first offset; determining a second offset basedon a position of the received downlink control channel; determining athird offset based on an index of an antenna port used at the UE toreceive the downlink control channel; mapping a linear combination ofthe first, second, and third offsets to an index identifying a firstallocated PUCCH resource; and transmitting a PUCCH on the firstallocated PUCCH resource.
 64. The method of claim 63, wherein the UEreceives a plurality of physical downlink shared channel (PDSCHs),respective ones of the PDSCHs being received in respective differentsubframes, and wherein the mapping of the linear combination comprisesadding a first subframe offset corresponding to a first subframe inwhich a first one of the PDSCHs was received.
 65. The method of claim63, further comprising: determining a second allocated PUCCH resource,the second allocated PUCCH resource having a value equal to the firstallocated PUCCH resource plus a constant; and transmitting a PUCCH onone of the first or the second allocated PUCCH resources using a firstantenna port.
 66. The method of claim 63, further comprising:determining a second allocated PUCCH resource, the second allocatedPUCCH resource having a value equal to the first allocated PUCCHresource plus a constant; and transmitting the PUCCH on the firstallocated PUCCH resource using a first antenna port and on the secondallocated PUCCH resource using a second antenna port, the PUCCH beingtransmitted simultaneously on the first and second antenna ports. 67.The method of claim 63, wherein the downlink control channel is in adownlink control information (DCI) format.
 68. The method of claim 63,further comprising: determining a fourth offset based on a transmissionmode of the downlink control channel, wherein the transmission mode isone of localized transmission or distributed transmission; and mapping alinear combination of the first, second, third, and fourth offsets tothe index identifying the first allocated PUCCH resource.
 69. The methodof claim 63, further comprising: normalizing the position of thereceived downlink control channel to form a normalized resource index;and mapping the normalized resource index to form the second offset. 70.A user equipment (UE), comprising: a memory; and at least one hardwareprocessor communicatively coupled with the memory and configured to:receive a downlink control channel carrying a physical uplink controlchannel (PUCCH) resource indicator; map the PUCCH resource indicator toa first offset; determine a second offset based on a position of thereceived downlink control channel; determine a third offset based on anindex of an antenna port used at the UE to receive the downlink controlchannel; map a linear combination of the first, second, and thirdoffsets to an index identifying a first allocated PUCCH resource; andtransmit a PUCCH on the first allocated PUCCH resource.
 71. The UE ofclaim 70, wherein the UE receives a plurality of physical downlinkshared channel (PDSCHs), respective ones of the PDSCHs being received inrespective different subframes, and wherein the mapping of the linearcombination comprises adding a first subframe offset corresponding to afirst subframe in which a first one of the PDSCHs was received.
 72. TheUE of claim 70, wherein the at least one hardware processor is furtherconfigured to: determine a second allocated PUCCH resource, the secondallocated PUCCH resource having a value equal to the first allocatedPUCCH resource plus a constant; and transmit a PUCCH on one of the firstor the second allocated PUCCH resources using a first antenna port. 73.The UE of claim 70, wherein the at least one hardware processor isfurther configured to: determine a second allocated PUCCH resource, thesecond allocated PUCCH resource having a value equal to the firstallocated PUCCH resource plus a constant; and transmit the PUCCH on thefirst allocated PUCCH resource using a first antenna port and on thesecond allocated PUCCH resource using a second antenna port, the PUCCHbeing transmitted simultaneously on the first and second antenna ports.74. The UE of claim 70, wherein the downlink control channel is in adownlink control information (DCI) format.
 75. The UE of claim 70,wherein the at least one hardware processor is further configured to:determine a fourth offset based on a transmission mode of the downlinkcontrol channel, wherein the transmission mode is one of localizedtransmission or distributed transmission; and map a linear combinationof the first, second, third, and fourth offsets to the index identifyingthe first allocated PUCCH resource.
 76. The UE of claim 70, wherein theat least one hardware processor is further configured to: normalize theposition of the received downlink control channel to form a normalizedresource index; and map the normalized resource index to form the secondoffset.
 77. A method in an access node, comprising: transmitting, to auser equipment (UE), a downlink control channel carrying a PUCCHresource indicator; mapping the PUCCH resource indicator to a firstoffset; determining a second offset based on a position of thetransmitted downlink control channel; determining a third offset basedon an index of an antenna port to be used at the UE to receive thedownlink control channel; mapping a linear combination of the first,second, and third offsets to an index identifying a first allocatedPUCCH resource; and receiving a PUCCH on the first allocated PUCCHresource.
 78. The method of claim 77, wherein a plurality of physicaldownlink shared channels (PDSCHs) are to be transmitted to the UE,respective ones of the PDSCHs being transmitted in respective differentsubframes, and wherein the mapping of the linear combination comprisesadding a first subframe offset corresponding to a first subframe inwhich a first one of the PDSCHs is to be transmitted.
 79. The method ofclaim 77, further comprising: determining a second allocated PUCCHresource, the second allocated PUCCH resource having a value equal tothe first allocated PUCCH resource plus a constant; and receiving aPUCCH on one of the first or the second allocated PUCCH resources usinga first antenna port.
 80. The method of claim 77, further comprising:determining a second allocated PUCCH resource, the second allocatedPUCCH resource having a value equal to the first allocated PUCCHresource plus a constant; and receiving the PUCCH on the first allocatedPUCCH resource using a first antenna port and on the second allocatedPUCCH resource using a second antenna port, the PUCCH being receivedsimultaneously on the first and second antenna ports.
 81. The method ofclaim 77, wherein the downlink control channel is in a downlink controlinformation (DCI) format.
 82. The method of claim 77, furthercomprising: determining a fourth offset based on a transmission mode ofthe downlink control channel, wherein the transmission mode is one oflocalized transmission or distributed transmission; and mapping a linearcombination of the first, second, third, and fourth offsets to the indexidentifying the first allocated PUCCH resource.